HTPD 2018

America/Los_Angeles

1404 Vacation Rd, San Diego, CA 92109
Description

The HTPD 2018 conference information can be found at the following link:

SanDIegoHTPD2018.com

• Sunday, 15 April
• 16:00 19:00
• 18:00 20:00
• Monday, 16 April
• 07:00 08:15
Breakfast: Sunset Pavilion (behind conference center)
• 07:00 10:00
• 08:30 08:45
Welcoming Words: - Chair: R. Boivin
• 08:45 10:45
Session #1, Monday Morning Invited Talks, Chair: D. Brower
• 08:45
1.1 Tests of a Full-Scale ITER Toroidal Interferometer and Polarimeter (TIP) Prototype 30m

A full-scale ITER toroidal interferometer and polarimeter (TIP) prototype has been constructed and tested both in the laboratory and on the DIII-D tokamak. The TIP prototype measures electron density using two approaches. Two-color interferometry is carried out at 10.59μm and 5.22μm using a CO2 and Quantum Cascade Laser (QCL) respectively while a separate polarimetry measurement of the plasma induced Faraday effect, is made at 10.59μm. High-resolution TIP phase information is obtained using an FPGA based phase demodulator and precision clock source. The TIP is also equipped with a piezo tip/tilt stage active feedback alignment system which minimizes noise and maintains diagnostic alignment indefinitely. A 120 m path length laboratory prototype was used to test components and demonstrate alignment techniques, feedback alignment capabilities, and determine diagnostic noise floors. Phase errors of 1.5 degrees for the interferometer and 0.06 degrees for the polarimeter have been demonstrated for 1000 seconds. The system is now operational on the DIII-D tokamak, using a geometry and path length similar to ITER, and has successfully demonstrated the ITER requirements for both interferometry and polarimetry. Work supported by U.S. DOE Contracts DE-AC-02-09CH11466 and DE-FC02-04ER54

Speaker: Michael Van Zeeland (General Atomics)
• 09:15
1.2 A High-Throughput, Pulse-Front-Tilt–Compensated Streaked Spectrometer for Picosecond Optical Thomson Scattering from Electron Plasma Waves 30m

A novel optical spectrometer was built that enables measurements of Thomson scattering from electron plasma waves with 2-ps time resolution. Pulse-front tilt introduced from a diffraction grating scales with aperture diameter and can limit the achievable time resolution of a streaked spectrometer. The spectrometer presented in this work uses an echelon optic to break the aperture into series of temporally delayed segments that compensate for the large-scale optical path length asymmetry introduced by the grating. By decoupling the relationship between pulse-front tilt and aperture size, an optimized spectrometer design can be matched to the time resolution of the streak camera at an arbitrarily large throughput. The as-built streaked spectrometer operates with an effective aperture of f/3.3 with 1-nm spectral resolution covering a range of 460 nm to 590 nm and records spectra with 2-ps time resolution. The system has been implemented to study plasma heating rates of underdense plasmas by observing Thomson scattering from electron plasma waves. This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0001944.

Speakers: Joseph Katz (LLE), Robert Boni (LLE), Andrew Davies (LLE ), Dustin Froula (LLE)
• 09:45
1.3 A combined interferometer/phase contrast imaging diagnostic for multiscale fluctuation measurements 30m

A novel combined diagnostic capable of measuring multiscale density fluctuations that extend from MHD to the lower-ETG range has been designed, installed, and operated at DIII-D. The combined diagnostic was constructed by adding a heterodyne interferometer to the pre-existing phase contrast imaging (PCI) system, both of which measure line-integrated electron-density fluctuations. The port-space footprint is minimized by using a single CO2 laser and a single beampath. With temporal bandwidths in excess of 1 MHz, the PCI measures high-k (1.5 cm^{-1} < |k_R| < 25 cm^{-1}) fluctuations with sensitivity 3e13 m^{-2} / \sqrt{kHz}, while the interferometer simultaneously measures low-k (|k_R| < 5 cm^{-1}) fluctuations with sensitivity 3e14 m^{-2} / \sqrt{kHz}. The intentional mid-k overlap has been empirically verified with sound-wave calibrations and has allowed quantitative investigation of the cross-scale coupling predicted to be significant in the reactor-relevant T_e ~ T_i regime. Further, via toroidal correlation with DIII-D's primary interferometer, the toroidal mode numbers of core-localized MHD have been measured. *Work supported by USDOE under DE-FG02-94ER54235, DE-FC02-04ER54698, and DE-FC02-99ER54512.

Speakers: Evan Davis (MIT PSFC), J. Chris Rost (MIT PSFC), Miklos Porkolab (MIT PSFC), Alessandro Marinoni (MIT PSFC), Michael Van Zeeland (General Atomics)
• 10:15
1.4 Dual Laser Holography for In-Situ Measurement of Plasma Facing Component Erosion 30m

A digital holography (DH) surface erosion/deposition diagnostic is being developed for 3D imaging of plasma facing component (PFC) surfaces in situ and in real time. Digital holography is a technique that utilizes lasers reflected from a material surface to form an interferogram, which carries information about the topology of the surface when reconstructed. As described in this paper, dual CO2 lasers at 9.271 and 9.250 microns illuminate the interrogated surface (at a distance of ~ 1 m) in a region of ~ 1 cm x 1 cm. The surface feature resolution is ~ 0.1 mm in the plane of the surface, and the depth resolution ranges from ~ 0.001 to ~2 mm perpendicular to the surface. The depth resolution lower limit is set by single-laser and detector optical limitations, while the upper limit is determined by 2 pi phase ambiguity of the dual-laser synthetic wavelength. Measurements have been made “on the bench” to characterize the single-laser and dual-laser DH configurations utilizing standard resolution targets and material targets that were previously exposed to high flux plasmas either in the Prototype Material Plasma Exposure eXperiment (Proto-MPEX) or electro-thermal (ET) arc source. Typical DH measurements were made with 0.03 ms integration with an IR camera that can be framed at rates approaching 1.5 kHz. The DH diagnostic system is progressing towards in situ measurements of plasma erosion/deposition either on Proto-MPEX or the ET arc source.

Speakers: Theodore Biewer (Oak Ridge National Lab.), Clarence Thomas (Third Dimension Technologies), Cary Smith (University of Tennessee), Jordan Sawyer (University of Tennessee)
• 10:45 13:00
Session #2, Monday Morning Poster Session
• 10:45
2.1 Measurement of apparent ion temperature using the magnetic recoil spectrometer at the OMEGA laser facility 2h

The Magnetic Recoil neutron Spectrometer (MRS) at the OMEGA laser facility has been routinely used to measure deuterium-tritium (DT) yield and areal density in cryogenically layered implosions since 2008. Recently, operation of the OMEGA MRS in higher-resolution mode with a smaller, thinner (4 cm2, 57-um thick) CD conversion foil has also enabled inference of the apparent DT ion temperature (Tion) from MRS data. Tion inferred from the broadening of the MRS-measured primary DT neutron spectrum compares well with neutron time-of-flight-measured Tion. This result is important as it demonstrates good understanding of the different systematics associated with the two independent measurements. The MRS resolution in this configuration (sigma=0.37 MeV) is still higher than required for a high-precision Tion measurement. In this contribution, we also discuss paths forward for further improving the resolution of the OMEGA MRS, including fielding a smaller foil closer to target chamber center. This work was supported in part by the U.S. Department of Energy and by the Laboratory of Laser Energetics under Contract 415935-G.

Speakers: Maria Gatu Johnson (MIT PSFC), Johan Frenje (MIT PSFC), Cody Parker (MIT PSFC), Fredrick Seguin (MIT PSFC), Chikang Li (MIT PSFC), Richard Petrasso (MIT PSFC), Chad Forrest (LLE), Vladimir Glebov (LLE), Joseph Katz (LLE), Craig Sangster (LLE), Christian Stoeckl (LLE), Michael Farrell (GA), Reny Paguio (GA), Michael Schoff (GA)
• 10:45
2.2 First Mirror Test in JET for ITER: causes for reflectivity degradation 2h

Metallic first mirrors will be components for optical spectroscopy and imaging systems in ITER. A comprehensive First Mirror Test (FMT) was carried out in JET with the ITER-Like Wall (ILW): over 60 Mo mirrors facing plasma in the main chamber and in divertor during three ILW campaigns (up to 62 h total). Reflectivity measurements (300-2400 nm) and surface characterization with electron and ion spectroscopy were done before and after exposure. Total reflectivity of mirrors from the main chamber wall is decreased by 2-3% from the initial value. Surfaces are coated by a thin co-deposit (5-15 nm) containing D, Be, C and O. This affected the optically active layer (15-20 nm on Mo) thus leading to the increase of diffuse reflectivity by a factor of 1-2. All mirrors from the divertor (inner, outer, base) lost reflectivity by 20-80%. This result confirms earlier findings, but there are significant differences in the surface state dependent on the mirror location and exposure time, i.e. either single or all three ILW campaigns. This is caused by beryllium-rich deposits. The thickest layers are in the outer divertor: 850 nm. Other elements also are in deposits on all divertor mirrors: O, C, W, and Ni. The comparison between results from JET with carbon and metal wall will be presented.

Speakers: Sunwoo Moon (Royal Institute of Technology (KTH)), Per Petersson (Royal Institute of Technology (KTH)), Marek Rubel (Royal Institute of Technology (KTH)), Anna Widdowson (Culham Centre for Fusion Energy)
• 10:45
2.3 High Detection Efficiency Scintillating Fiber Detector for Time-Resolved Measurement of Triton Burnup 14 MeV Neutron in Deuterium Plasma of Middle Size Tokamak 2h

The behavior of 1 MeV triton has been studied in order to understand alpha particle confinement property in toroidal devices. Time-resolved triton burnup study has been performed by scintillating fiber detectors (Sci-Fi) in large tokamaks [1] and helical systems [2]. The time-integrated triton burnup ratio was successfully measured by activation foils technique in medium sized tokamak [3, 4]. To obtain time evolution of 14 MeV neutron rate under the neutron emission rate of 10^13 n/s to 10^14 n/s in KSTAR, we designed high detection efficiency Sci-Fi having a diameter (f) of 160 mm. In the head of detector1, 2000 scintillating fibers having f of 1 mm and length of 50 mm are embedded, whereas 1000 scintillating fibers having f of 2 mm and length of 50 mm are embedded in the head of detector2. The detection efficiency of those detectors is expected to be one order higher than the detectors used in large tokamaks [1]. Experimental results performed using an accelerator-based neutron generator in Fast Neutron Laboratory and OKTAVIAN will be reported.[1] Barnes C. W. et al 1998 Nucl. Fusion 38 597.[2] K. Ogawa et al., submitted to Nuclear Fusion.[3] J. Jo. et al 2016 Rev. Sci. Instrum. 87 11D828.[4] M. Hoek et al., IPP-Report IPP 1/320 March 1999.

Speakers: Kunihiro Ogawa (National Institute for Fusion Science), Mitsutaka Isobe (National Institute for Fusion Science), Takeo Nishitani (National Institute for Fusion Science), Eiji Takada (National Institute of Technology, Toyama Collage), Hiroki Kawase (SOKENDAI (The Graduate University for Advanced Studies)), Neng Pu (SOKENDAI (The Graduate University for Advanced Studies)), Tatsuki Amitani (National Institute of Technology, Toyama Collage), Jungmin Jo (Seoul National University), Munseong Cheon (National Fusion Research Institute), Shigeo Matsuyama (Tohoku University), Isao Murata (Osaka University)
• 10:45
2.4 Using Motional Stark Splitting of Dα Emission to Constrain MHD Equilibrium Analysis in DIII-D Plasmas 2h

We report tests of an alternate technique for constraining MHD equilibrium analysis in tokamak plasmas using internal magnetic field measurements based on |B| measurements from motional Stark splitting of Dα spectral lines emitted by a neutral heating beam (MSE-LS). We compare results using MSE-LS with those of the standard equilibrium analysis technique based on line polarization of the Dα emission (MSE-LP). An alternative to MSE-LP is needed in future devices such as ITER where MSE-LP will be difficult due to plasma-induced coating of the first optical element. The tests utilized data from 10 DIII-D shots with 7 MSE-LS and 14 MSE-LP views covering a range of radii along the outer midplane of the plasma. Seven MSE-LS measurements can contribute significantly to equilibrium reconstruction of pressure and q profiles using both synthetic and experimental DIII-D MSE-LS data. For example, 7 MSE-LS plus seven MSE-LP measurements give a fit quality that is as good as the same cases with 14 MSE-LP measurements. Analyzing synthetic data for 14 MSE-LS measurements shows significant improvement in fitting quality over the case with 7 MSE-LS locations. This work supported by DoE DE-FC02-04ER54698 and DE-AC02-09CH11466.

Speaker: Keith Burrell (General Atomics)
• 10:45
2.5 Microscope requirements to diagnose high-spatial-frequency bright spots in inertial confinement fusion implosions at the national ignition facility 2h

Inertial confinement fusion self-emission imaging provides a challenging environment for two-dimensional time resolved x-ray imaging. The short lived (~200 ps) spherical implosion dynamically evolves throughout the deuterium-tritium (DT) compression. Current microscopes with ~10 µm spatial resolution and 20-100 ps time resolution provide sufficient information to infer hot spot volume and emissivity under certain physical constraints. The introduction of high-atomic number materials as shell dopants, in conjunction with the susceptibility of the implosion to seeded hydrodynamic growth, has led to continued observations of high-spatial-frequency x-ray bright spots that evolve internally to the hot DT core. We wish to determine the origin and nature of these features through the application of higher resolution x-ray microscopes. This goal requires addressing both the image forming system and the detector resolution and statistics, in addition to the physics we hope to infer. With new reflective x-ray optics and coded aperture imaging being considered alongside the next generation of fast x-ray detectors, this paper addresses the instrument design requirement to measure ‘bright spot’ features at the NIF. Prepared by LLNL under Contract DE-AC52-07NA27344. LLNL-ABS-744014.

Speaker: Louisa Pickworth (LLNL)
• 10:45
2.6 Development of the multi-pass Thomson scattering system with the laser amplification system 2h

Thomson scattering (TS) system is one of the useful diagnostics to measure electron temperature and density in fusion plasmas. The multi-pass Thomson scattering (MPTS) system is useful technique for increasing the TS signal intensities and improving the TS diagnostic time resolution. The MPTS system developed in GAMMA 10/PDX has a polarization-based configuration with an image relaying system. The MPTS system has been constructed for enhancing the Thomson scattered signals for the improvement of measurement accuracy and the MHz sampling time resolution. However, in the normal MPTS system, the MPTS signal intensities decrease with the pass number, because of the damping due to the constructed optical components. Then we have been developing the new MPTS system with the laser amplification system. The laser amplification system can improve the degraded laser power after six passed in the multi-pass system to the initial laser power. We successfully obtained the continued multi-pass signals after the laser amplification system in the gas scattering experiments for the first time.

Speaker: Masayuki Yoshikawa (Plasma Research Center, University of Tsukuba)
• 10:45
2.7 Simultaneous measurement of CVI, NeX and LiIII charge exchange lines on EAST 2h

Charge exchange spectra from the interaction of fully ionized Carbon impurity ions and injected neutral beam on EAST have been utilized to provide the plasma ion temperature and rotation velocity since the cCXRS was installed on EAST at 2014. However, the concentration of carbon became especially low on EAST with the tungsten divertor in the latest experimental campaign, it is necessary to investigate the CX lines from the other impurity ions. The cCXRS system was enhanced recently to extend its wavelength coverage and preserve the spatial channels at the same time. A pixel, back-illuminated frame-transfer CCD camera with on-chip multiplication gain was used. The bandpass filter centered on 529.1nm was removed and one entrance slit was used to enable a wide spectral band at one acquisition, and the emission lines of CVI at 529.1 nm, of NeX at 524.9 nm, and of LiIII at 516.7 nm could be observed simultaneously. The system contains 29 channels, and one channel is used for the real-time wavelength calibration. The simultaneous measurement of CVI, NeX, and LiIII lines was performed by puffing neon gas and dropping lithium power at the same time during the 2016 EAST experimental campaign. In the paper, the experimental hardware is described and preliminary measurements will be shown.

Speakers: Yingying Li (Institute of Plasma Physics, Chinese Academy of Sciences), Yixuan Zhou (School of Nuclear Science and Technology, University of Science and Technology of China), Di Jiang (Institute of Plasma Physics, Chinese Academy of Sciences), Wei Tao (School of Nuclear Science and Technology, University of Science and Technology of China), Ze Chen (School of Nuclear Science and Technology, University of Science and Technology of China), Jia Fu (Institute of Plasma Physics, Chinese Academy of Sciences), Bo Lyu (Institute of Plasma Physics, Chinese Academy of Sciences), Yuejiang Shi (Department of Nuclear Engineering, Seoul National University), Minyou Ye (School of Nuclear Science and Technology, University of Science and Technology of China), Baonian Wan (Institute of Plasma Physics, Chinese Academy of Sciences)
• 10:45
2.8 Velocity-space sensitivity of the time-of-flight neutron spectrometer of EAST deuterium plasmas 2h

Self-sustaining fusion plasmas must be maintained by the power transfer from fusion born alpha particles to the thermal plasmas during slowing down process. Thus, the confinement of energetic alpha particles is crucial for a thermonuclear reactor in the future. The fast ions are primarily generated by applying auxiliary heating systems such as neutral beam injection and ion cyclotron resonance heating in current experiments. The information of the fast ions can be accessed by different fast-ion diagnostic systems. The velocity-space sensitivities of fast-ion diagnostics are given by so-called weight functions. The Time-Of-Flight Enhanced Diagnostics (TOFED) neutron spectrometer has been installed at EAST tokamak to perform advanced neutron emission spectroscopy (NES) diagnosis of deuterium plasmas. Here, instrument-specific weight functions of TOFED were presented by taking the instrumental response into account. The velocity-space sensitivity of a measured time-of-flight spectrum from TOFED can be directly determined by the calculated weight functions.

Speaker: Lijian Ge (Peking University)
• 10:45
2.9 Laser Induced Fluorescence for Singly Ionized Atomic Iodine 2h

While xenon is the standard propellant for a wide range of plasma thrusters, xenon is expensive and xenon propellant systems require heavy compressed gas tanks, pressure regulators, and other bulky hardware. Iodine has similar mass and is much easier to acquire than xenon. Iodine’s natural state of matter at room temperature is solid and is easily sublimated to gas with a simple heating element. This advantage for iodine is also a significant challenge when developing gas handling systems for iodine. Another challenge for iodine thrusters is a lack of well-defined spectroscopic diagnostics for single ionized iodine, specifically, a lack of a demonstrated laser induced fluorescence (LIF) scheme. We present emission spectroscopy measurements of iodine ion emission from the 6p^5P_3-5d^5 D_4^o transition at 695.868 nm and the 6p^5P_3-6s^5S_2^o transition at 516.12 nm as a function of microwave power for a microwave excited iodine plasma in a sealed quartz cell at a pressure of 1 mTorr. The 5d^5D_4^o state is metastable and was identified by Hargus et al. [48th AIAA Joint Propulsion, 2012] as a strong candidate for an iodine ion LIF scheme. We will also present preliminary LIF measurements using this three-level scheme with a tunable dye laser operating at 695.878 nm.

Speakers: Thomas Steinberger (West Virginia University), Earl Scime (West Virginia University)
• 10:46
2.10 Multi-Angled Multi-Pulsed Time-Resolved Thomson Scattering on Laboratory Plasma Jets 2h

Streaked Thomson scattering measurements have been performed on plasma jets created from a 15 µm thick radial Al, Ti, or Cu foil load on COBRA, a 1 MA pulsed power machine. The streaked system enables collecting scattered light from two separate laser pulses separated in time by between 3 and 14 ns. This time difference is created by splitting the initial 3 ns duration, 10 J, 526.5 nm laser beam into two separate pulses, each with 2.5 J. Both energy laser pulses are shown to heat the plasma jet by inverse bremsstrahlung radiation, as measured by the streaked Thomson scattering system. Analysis of the streak camera image showed that the electron temperature of the Al jet was increased from 20 eV up to 50 eV within about 2 ns for both laser pulses. The Ti and Cu jets both showed heating as well as sharp and complicated ion-acoustic features that were not apparent in the Al jet. Results will be presented from imaging two different fibers that viewed the plasma jet from two different scattering angles on the streak camera entrance slit simultaneously to compare temperature measurements and have a measure of the plasma density [Froula et al. PRL 2005].This research is supported by the NNSA Stewardship Sciences Academic Programs under DOE Cooperative Agreement DE-NA0001836.

Speakers: Jacob Banasek (Cornell University), Tom Byvank (Cornell University), Sophia Rocco (Cornell University), William Potter (Cornell University), Bruce Kusse (Cornell University), David Hammer (Cornell University)
• 10:46
2.11 Presenting the characterisation of a Pulse Dilation Photo Multiplier Tube intended for use with a gamma-ray sensitive Gas Cherenkov Detector at NIF 2h

A pulse dilation photo-multiplier tube (PD-PMT) is a newly developed capability, which improves on the temporal resolution of conventional PMTs by approximately an order of magnitude. The corresponding gains in detail of inertial confinement fusion burn histories (10's of picoseconds wide in experiments in the National Ignition Facility), could be used to distinguish overlapping burn histories of different reactants.A PD-PMT uses a decreasing voltage ramp to apply a time varying e-field acceleration to electrons generated by a photocathode to stretch the signal in time (dilate). As earlier electrons are accelerated more than later electrons, the signal is dilated to improve resolution in a short (~ns) time window. A production PD-PMT was characterised at the Orion laser using the Optical Pulse Generator of the short pulse lasers. The PD-PMT was tested by varying operating parameters, input laser pulses, separations of a laser input pulses, and the position of the input laser pulses relative to the start of the ramped voltage (dilation window scan). As well varying the input intensity to quantify the linearity, and translating an apertured beam across the photocathode to assess the spatial uniformity. This poster will outline the characterised performance of the PD-PMT.

Speaker: Alex Leatherland (AWE)
• 10:46
2.12 A Wolter Imager on the Z Machine to Diagnose Warm X-ray Sources 2h

We have developed a Wolter x-ray imager on the Z Machine to study the emission of warm x-ray sources with x-ray energies above 15 keV. As x-ray energy increases, imaging these sources with both high resolution and signal-to-noise becomes increasingly difficult using existing pinhole camera techniques. A Wolter optic has been adapted from observational astronomy and medical imaging for Z and uses curved x-ray mirrors to form a 2D image of a source with 5x5x5mm FOV and measured 180-μm resolution on-axis. The mirrors consist of a multilayer that is tuned to allow x-rays within a narrow energy band to be collected by the optic. This multilayer, along with the larger collection solid angle makes the Wolter optic much more efficient at imaging x-rays compared to a traditional pinhole camera. Here we present the experimental design and implementation of the Wolter x-ray imager on Z, which is initially optimized to view Mo K-alpha x-rays (17.5 keV). In addition, we present a brief overview of its measured imaging performance and considerations for image deblurring.

Speakers: Jeffrey R. Fein (Sandia National Laboratories), David Ampleford (Sandia National Laboratories), Julia K. Vogel (Lawrence Livermore National Laboratory), Bernie Kozioziemski (Lawrence Livermore National Laboratory), Chris Walton (Lawrence Livermore National Laboratory), Ming Wu (Sandia National Laboratories), Andrew Ames (Harvard Smithsonian Center for Astrophysics), Jay Ayers (Lawrence Livermore National Laboratory), Christopher R. Ball (Sandia National Laboratories), Perry Bell (Lawrence Livermore National Laboratory), Christopher Bourdon (Sandia National Laboratories), David Bradley (Lawrence Livermore National Laboratory), Ricardo Bruni (Harvard Smithsonian Center for Astrophysics), Paul Gard (Sandia National Laboratories), Patrick Lake (Sandia National Laboratories), Andrew Maurer (Sandia National Laboratories), Louisa Pickworth (Lawrence Livermore National Laboratory), Michael Pivovaroff (Lawrence Livermore National Laboratory), Brian Ramsey (NASA Marshall Spaces Flight Center), Kiranmayee Kilaru (Universities Space Research Association), Oliver Roberts (Universities Space Research Association), Suzanne Romaine (Harvard Smithsonian Center for Astrophysics)
• 10:46
2.13 Development of an optical Thomson scattering system for the Orion laser 2h

Optical Thomson scattering (OTS) can be used to provide temporally and spectrally-resolved information on under-dense, high temperature plasmas. Scattering from the high-frequency collective excitations of the electrons can be used to constrain the temperature and number density of the electrons based on the width, amplitude and location of resonances in the scattered spectrum. The ion acoustic spectral features provide estimates of the ion and electron temperature ratio as well as the plasma mean ionisation state. These spectra can be streaked allowing the time evolution of the plasma conditions to be studied. In this presentation we discuss the development of an OTS diagnostic for the Orion laser system at AWE, UK. A 3ω probe beam will be used and the light scattered by the volume of plasma under study will be collected using a reflective telescope system. Light from the ion and electron features can be split into two spectrometers, one covering the narrow bandwidth of the acoustic waves with high resolution and a second spectrometer to cover the broader wavelength range of the plasma waves. Time resolved data can then be obtained by relaying the spectrally resolved signal onto an optical streak camera. © British Crown Owned Copyright 2018/AWE

Speakers: Lucy Wilson (AWE Plc.), Steven James (AWE Plc.), Kevin Oades (AWE Plc.)
• 10:46
2.14 Velocity-space sensitivity of the compact neutron emission spectrometers at EAST 2h

Several compact neutron spectrometers are now installed at EAST to obtain the information of fuel ions produced in core plasmas. Here, a stilbene and an NE213 liquid scintillator neutron spectrometers will be discussed. Both of the spectrometers have a horizontal line of sight, while at different positions, and are proved to show good performance when the NBI auxiliary heating system is applied. Taking the response function into consideration, the velocity-space sensitivities given by the instrument-specific weight function of the beam-thermal part of neutron energy spectra in D-D plasma are derived for both the spectrometers. This method is supposed to make it possible to directly determine the contribution from a given velocity-space distribution of the fast ions to the measurement results.

Speaker: Yimo ZHANG (Peking University)
• 10:46
2.15 Modeling the One-Dimensional Imager of Neutrons (ODIN) for Neutron Response Functions at the Sandia Z Facility 2h

The one-dimensional imager of neutrons (ODIN) at the Sandia Z facility consists of a 10-cm block of tungsten with rolled edges, creating a slit imager width of either 250, 500, or 750 µm. Designed with a 1-m neutron imaging line of sight, we achieve about 4:1 magnification and 500-µm axial spatial resolution. The baseline ICF concept at Sandia is magnetized liner inertial fusion (MagLIF), which nominally creates a 1-cm line source of neutrons. ODIN was designed to determine the size, shape, and location of the neutron producing region, furthering the understanding of compression quality along the cylindrical axis of magnetized liner implosions. Challenges include discriminating neutron images from hard x-rays and gammas with adequate signal-to-noise in the 2e12 DD neutron yield range, as well as understanding the neutron response function through the imager to various imaging detectors (namely CR-39). Modeling efforts were conducted with MCNP6.1 to determine neutron response functions for varying configurations in a clean DD neutron environment (without x-rays or gammas). Configuration alterations that will be shown include rolled-edge slit orientation and slit width, affecting resolution and response function.Work supported by DOE NNSA contract DE-NA0003525.

Speakers: Jeremy Vaughan (University of New Mexico), Carlos Ruiz (Sandia National Laboratories), David Fittinghoff (2Lawrence Livermore National Laboratory), Mark May (2Lawrence Livermore National Laboratory), David Ampleford (1Sandia National Laboratories), Gary Cooper (University of New Mexico), Gordon Chandler (1Sandia National Laboratories), Kelly Hahn (1Sandia National Laboratories), Perry Alberto (1Sandia National Laboratories), Jose Torres (1Sandia National Laboratories), Brent Jones (1Sandia National Laboratories)
• 10:46
2.16 Developing a Fast Visible Camera Diagnostic for 2D-Measurements of the Balmer Series and Impurity Emission Lines in Proto-MPEX Plasma Discharges 2h

The Prototype Material Plasma Exposure eXperiment (Proto-MPEX) is a linear plasma device designed to generate divertor-like conditions, yielding electron densities up to ~1020 m-3 and electron temperatures up to ~20 eV. Monochromatic and color Edgertronic Sanstreak SC1 fast visible cameras capture high speed video (<18k fps) of plasma discharges. A 50/50 beam splitter allows both cameras to image the same region of the discharge. Concurrent multi-camera 2D line-integrated images were made of two or more emission line fields using narrow-band transmission filters. The deuterium Balmer series dominates the visible emission spectra from Proto-MPEX, confirmed via broadband spectrally resolved measurements. Under certain conditions, such as gas puffing, impurity line emissions were observed. Spatial features from multiple spectral line images were compared. Also, a uniform intensity white light source was used to calibrate pixel-to-pixel and absolute intensities. From this, the Dα, Dβ, and Dγ intensity ratio 2D fields and the 2D n0 and ne fields were estimated. Comparisons were drawn between line-integrated and Abel inverted emission (r,z) profiles. Discussion includes the limitations of the multi-camera technique and measured plasma material interactions (PMI) at the target plate.

Speakers: Elizabeth Lindquist (Oak Ridge National Laboratory, Hope College), Theodore Biewer (Oak Ridge National Laboratory), Holly Ray (University of Tennessee), Clyde Beers (University of Tennessee)
• 10:46
2.17 Upgrade of the ECE diagnostic on EAST 2h

The ECE diagnostic on EAST has been recently upgraded to provide better radial coverage of the plasma and to obtain higher spatial resolution. The lower limit of the frequency band was extended from 104 GHz to 97 GHz by adding a new 8-channel radiometer system, and this ensures a capability of measuring the second harmonic ECE with toroidal magnetic field down to 1.75 T. Also, the existing 32-channel radiometer has been upgraded, with the frequency interval for the lower frequency range up to 120 GHz reduced from 2 GHz to 1 GHz by introducing eight channels in the intermediate frequency part. In addition, a plan is presented to incorporate tunable YIG filters into the existing radiometer system to obtain detailed measurements of the electron temperature gradient scale length as well as finer spatial pinpointing of MHD modes. Examples from DIII-D are provided where similar high resolution channels allowed more precise measurement of the center and width of neoclassical tearing modes. *This work is supported by the National Magnetic Confinement Fusion Science Program of China under Contract No. 2015GB101000 and 2015GB103000 and US Department of Energy under contracts DE-FG02-97ER54415, DE-FC02-04ER54698 and DE-SC0010500.

Speakers: hailin zhao (university of texas), tianfu zhou (Institute of Plasma Physics), yong liu (Institute of Plasma Physics), Saeid Houshmandyar (Institute for Fusion Studies ), William Rowan (Institute for Fusion Studies ), He Huang (Institute for Fusion Studies ), Max Austin (Institute for Fusion Studies ), liqun hu (Institute of Plasma Physics)
• 10:46
2.18 Real-Time Digital Phase Demodulator for the ITER Toroidal Interferometer and Polarimeter (TIP) 2h

The ITER TIP system requires real time phase demodulation of several radio-frequency (RF) signals to provide accurate electron density measurements essential for plasma control. This is accomplished using a four-channel digital phase demodulator (DPD) constructed using a high-density Field Programmable Gate Array (FPGA) coupled to high-speed analog-to-digital converters (ADC). The DPD samples signals from four optical detectors each containing frequencies at 4, 40, and 44MHz. Digital signal processing (DSP) techniques are used to separate the three frequencies and measure their phase. Two versions of DPDs have been constructed and tested on the DIII-D TIP system. The first was fabricated using a Xilinx Kintex-7 FPGA development board, a high-speed ADC module from Analog Devices, and custom hardware from Palomar Scientific Instruments. The second was assembled using ITER-approved components from National Instruments. The FPGA implementation for both versions was designed using Matlab System Generator and the VHDL programming language. Both systems have been shown to provide phase measurements with better than 0.01º accuracy at 500kHz bandwidth. Work supported by U.S. DOE Contracts DE-AC-02-09CH11466 and DE-FC02-04ER54698.

Speakers: Randy Allen Colio (Palomar Scientific Instruments), D.F. Finkenthal (Palomar Scientific Instruments), M.A. Van Zeeland (General Atomics), T.N. Carlstrom (General Atomics), A. Gatusso (General Atomics), R. O'Neill (General Atomics), R.L. Boivin (General Atomics), D. Johnson (Princeton Plasma Physics Laboratory)
• 10:46
2.19 Self-calibrating techniques for polarimetric Thomson scattering 2h

Polarimetric Thomson scattering (TS) is a diagnostic technique useful to increase the accuracy of Te and ne measurements in very hot fusion plasmas such as those of ITER. As for conventional TS the calibration of a polarimetric TS detection system can be performed by using a radiation source internal to the vacuum chamber or, alternatively, Raman scattering from N2 gas filling the vacuum vessel. These calibration methods are thought to be too invasive in case of a large fusion experiment and therefore for conventional TS measurements in ITER self-calibrating techniques have been proposed by which, using two laser pulses of different wavelegth, the spectral sensitivity of the detection system can be continuously monitored during the experimental campaigns, without the need of invasive internal sources. In this paper we extend the concept of self-calibrating measurements to the polarimetric TS technique too. By exploiting the polarization properties of TS scattering light and two laser pulses of different polarization, we show that self-calibrating measurements are possible also for a TS detection system including polarimetric measurements and indicate simple methods for its implementation.

Speakers: Leonardo Giudicotti (Padova University), Roberto Pasqualottto (Consorzio RFX), Oisin McCormack (Consorzio RFX)
• 10:46
2.20 Self-Calibration of Electron Cyclotron Emission Imaging with Shape Matching 2h

Electron Cyclotron Emission Imaging (ECEI) is a diagnostics system which measures 2D electron temperature pro?les of high-temperature plasma. Magnetohydrodynamics(MHD) modes in fusion plasma can be quantitatively studied by of ECEI after calibration (fi?nding the proportional coe?cients of electron temperature to signal amplitude). Conventional calibrating methods are complecated and difficult to implement. In this paper we propose an self-dependent calibrating method for 24x16 channels high-resolution ECEI on EAST Tokamak based on the properties of data, in which the technique of shape matching is applied to solve for calibration coe?cients matrix. The calibrated area is further expanded to a occupation ratio of 88% detecting area by utilizing the features of sawtooth crash. The result is self-consistent and agrees with other experimental data, supporting the validity of this self-calibration approach.

Speaker: Jinlin Xie (Dept. of Modern Physics, university of science and technology of china)
• 10:46
2.21 Signal to noise ratio of upgraded imaging bolometer for KSTAR 2h

An InfraRed imaging Video Bolometer (IRVB) [1,2] that was previously used on the JT-60U device [3] was installed on KSTAR in 2012. The IRVB had a 2 micron x 7 cm x 9 cm Pt foil blackened with graphite and a 5 mm x 5 mm aperture located 7.5 cm from the foil and had 16 x 12 channels and a time resolution of 10 ms. In 2017 the IRVB was upgraded by replacing the IR camera with a FLIR SC7600 (InSb, 640 x 512 pixels, 105 fps, 25 mK). The aperture area was reduced by approximately half to 3.5 mm x 3.5 mm and the number of channels was quadrupled to 32 x 24. Assuming a uniformly radiating plasma of 15 m3 and 1 MW of radiated power and a viewing path length through the plasma of 3 m, the signal level on the foil was estimated to be 55 W/m2 in the previous case and 27 W/m2 with the upgrade. The resulting NEPDs (signal to noise ratios (SNR)) were 1.28 W/m2 (43) in the previous case and 2.35 W/m2 (12) with the upgrade. In the conference presentation synthetic images from SOLPS modelling will be compared with experimental images from the upgraded IRVB to give better estimates of the SNR. [1] B.J. Peterson, Rev. Sci. Instrum. 71(10) (2000) 3696. [2] B.J. Peterson et al., Rev. Sci. Instrum. 74(3) (2003) 2040. [3] B.J. Peterson et al., Rev. Sci. Instrum.79 (2008) 10E301.

Speakers: Byron Jay Peterson (National Institute for Fusion Science), Seungtae Oh (National Fusion Research Institute), Dongcheol Seo (National Fusion Research Institute), Juhyeok Jang (Korea Advanced Institute of Science and Technology), Kiyofumi Mukai (National Institute for Fusion Science), Jae Sun Park (Korea Advanced Institute of Science and Technology), Wonho Choe (Korea Advanced Institute of Science and Technology)
• 10:46
2.22 Measurement of argon impurity by X-ray imaging crystal spectrometer on J-TEXT 2h

A tangential X-ray imaging crystal spectrometer (XICS) has been upgraded on J-TEXT tokamak to measure the electron/ion temperature and the plasma toroidal rotation velocity. The XICS has been designed to receive emissions of Ar XVII from −13 cm to +13 cm region with a spatial resolution of 1.8 cm in the vertical direction. The temporal evolution of Ar impurity density profiles after an argon gas puff could be observed with a time resolution of up to 2 ms. The emissions of Ar XVII can be modulated by the resonant magnetic perturbations (RMPs) which indicates that the transport of Ar is affected by the RMP significantly. The 2/1 RMPs can lead to field penetration with enough RMP amplitude. The XICS provides a tool for the study of the transport of Ar impurities during the penetration of RMP. During the field penetration phase, the emissions of Ar XVII decreased and the profile of Ar XVII became narrow. The phenomena show that the transport of Ar impurity in the core region has been enhanced during the field penetration phase.

Speakers: Yan Wei (Huazhong University of Science and Technology), Chen Zhongyong (Huazhong University of Science and Technology), Tong Ruihai (Huazhong University of Science and Technology), Wei Yunong (Huazhong University of Science and Technology), Huang Duwei (Huazhong University of Science and Technology), Yang Zhoujun (Huazhong University of Science and Technology), Li You (Huazhong University of Science and Technology), Yang Huaiyu (Huazhong University of Science and Technology), Wang Duoqin (Huazhong University of Science and Technology), Li Wei (Huazhong University of Science and Technology)
• 10:46
2.23 First results of multi-channel scintillator-based SX diagnostic with P47 scintillator in deuterium plasma experiments of LHD and examination of method for design in EAST 2h

Multi-channel soft x-ray (SX) diagnostic has been used as a main diagnostic in fusion plasma devices to research MHD phenomena. Semiconductors have been widely used as SX diagnostic in magnetic confinement devices. However, it is difficult to use semiconductors in high neutron flux environment, such as deuterium plasma experiments of LHD, without radiation shielding. Therefore, a new type of SX diagnostic, scintillator-based SX diagnostic has been developed in LHD and EAST. In this type of the diagnostic, an SX from plasma is converted to visible light by the scintillator. The light is then guided to a remote location and measured there by detectors. In this article, first results of scintillator-based SX diagnostic with P47 scintillator in deuterium plasma experiments of LHD and in EAST are reported. The multi-channel system in LHD have observed the fluctuation by MHD instabilities then it can be said that the system have worked as multi-channel SX diagnostic. In EAST, there are two channels for scintillator-based SX diagnostics where one of two channels has SX shield. By comparing two channels, effect of neutrons and gamma-rays can be estimated experimentally. The examination of method to design scintillator-based SX diagnostics have been performed in EAST.

Speaker: Takahiro Bando (SOKENDAI)
• 10:46
2.24 The multi-channel Doppler Backscattering system on EAST 2h

Doppler backscattering (DBS) system is a powerful diagnostic for turbulence and ExB flow measurements on tokamaks and other magnetic confinement devices. A W-band multi-channel DBS system has been developed on EAST for the turbulence measurements in core plasma. The DBS system can provide six spatially localized measurement locations by simultaneously launching six frequency probe beams with a fixed frequency difference, and the center frequency can scan in W-band (75-108 GHz) with X-mode polarization. The incidence angle is from -8 to 12 degree, and can cover the wave number range 2-20/cm. The radial location coverage is depended on the parameter of discharge, and can always cover the range from the top of pedestal to the core of plasma.

Speakers: CHU ZHOU (University of Science and Technology of China), Adi Liu (University of Science and Technology of China), Xi Feng (University of Science and Technology of China)
• 10:46
2.25 The new magnetic diagnostics in the WEST tokamak 2h

The WEST (Tungsten [W] Environment in Steady-state Tokamak) tokamak aims at testing ITER divertor components to minimize risks for ITER divertor procurement and operation. It consists in a major upgrade of the superconducting medium size tokamak Tore Supra resulting in changing the circular magnetic configuration to a divertor configuration and implementing an ITER like actively cooled Tungsten divertor. Such modification has required rebuilding a full set of magnetic diagnostics to ensure the plasma boundary reconstruction, the plasma magnetic control and diamagnetic and MagnetoHydroDynamics measurements. For that purpose a set of 460 sensors has been integrated into the WEST vacuum vessel. After a brief description of the magnetic diagnostic specifications and integration, the paper discusses the commissioning of the diagnostic and the comparison with free boundary code reconstruction. The real time data processing providing the main plasma parameters is also presented. It is based on a description of the magnetic flux on a toroidal harmonic basis and is lasting less than 2 ms. The Simulink simulation framework used to test the equilibrium reconstruction and to develop the plasma controllers is described. Then results on plasma experiments and diagnostic performance are shown.

Speakers: Philippe Moreau (CEA), Alain Le-Luyer (CEA), Pascal Spuig (CEA), Philippe Malard (CEA), François Saint-Laurent (CEA), Jean-François Artaud (CEA), Blaise Faugeras (CNRS), Holger Heumann (CNRS), Bruno Cantone (CEA), Michel Moreau (CEA), Cyril Brun (CEA), Remy Nouailletas (CEA), Eric Nardon (CEA), Benjamin Santraine (CEA), Sunil Belsare (IPR)
• 10:46
2.26 Diagnostic Suite of the C-2W Advanced Beam-Driven Field-Reversed Configuration Plasma Experiment 2h

The new C-2W experiment (also called “Norman”) at TAE Technologies, Inc. studies the evolution of field-reversed configuration (FRC) plasmas sustained by neutral beam injection. Data on the FRC plasma performance is provided by a comprehensive suite of diagnostics that includes over 600 magnetic sensors, four interferometer systems, multi-chord far-infrared polarimetry, two Thomson scattering systems, ten types of spectroscopic measurements, multiple fast imaging cameras with selectable atomic line filters, bolometry, reflectometry, neutral particle analyzers, and fusion product detectors. Most of these diagnostic systems are newly built using experience and data from the preceding C-2U experiment [1] to guide the design process. In addition, extensive ongoing work focuses on advanced methods of measuring the internal FRC magnetic field profile to facilitate equilibrium reconstruction and active control of the plasma. 1] M. C. Thompson et al., Rev. Sci. Instrum. 87, 11D435 (2016)

Speakers: Matthew Thompson (TAE Technologies, Inc.), Tania Schindler (TAE Technologies, Inc.), Hiroshi Gota (TAE Technologies, Inc.), Sergei Putvinski (TAE Technologies, Inc.), Michl Binderbauer (TAE Technologies, Inc.), the TAE Team (TAE Technologies, Inc.)
• 10:46
2.27 First Measurements of a scintillator based Fast-Ion Loss Detector near the ASDEX Upgrade Divertor 2h

A new reciprocating scintillator-based fast-ion loss detector (FILD)1 has been installed a few centimeters above the outer divertor of the ASDEX Upgrade tokamak and between two of its lower ELM mitigation coils. The detector head containing the scintillator screen, Faraday cup, calibration lamp and collimator systems are installed on a motorized reciprocating system that can adjust its position via remote control in between plasma discharges. Orbit simulations are used to optimize the detector geometry and velocity-space coverage. The scintillator image is transferred to the light acquisition systems outside of the vacuum via a lenses relay (embedded in a 3D-printed titanium holder) and an in-vacuum image guide. A Charge Couple Device (CCD) camera, for high velocity-space resolution, and an 8x8 channels Avalanche Photo Diode (APD) camera, for high temporal resolution (up to 2MHz), are used as light acquisition systems. Initial results showing poloidally localized fast-ion losses due to Edge Localized Modes (ELMs) and externally applied 3D magnetic perturbations are discussed. Tomographic reconstruction techniques are used to infer the escaping ion velocity-space from direct measurements with unprecedented resolution. [1] M. Garcia-Munoz et al., RSI 80, 053503 (2009)

Speakers: Javier Gonzalez-Martin (Department of Mechanical and Manufacturing Engineering, University of Seville), Juan Manuel Ayllon-Guerola (Department of Mechanical and Manufacturing Engineering, University of Seville), Manuel Garcia-Munoz (Department of Atomic, Molecular and Nuclear Physics, Faculty of Physics, University of Seville), Albrecht Herrmann (Max-Planck-Institut für Plasmaphysik), Peter Leitenstern (Max-Planck-Institut für Plasmaphysik), Wolfgang Popken (Max-Planck-Institut für Plasmaphysik), Pascal De Marne (Max-Planck-Institut für Plasmaphysik), Zoletnik Sandor (Wigner RCP), Akos Kovacsik (Wigner RCP), Joaquin Galdon-Quiroga (Department of Atomic, Molecular and Nuclear Physics, Faculty of Physics, University of Seville), Juan Francisco Rivero-Rodriguez (Department of Mechanical and Manufacturing Engineering, University of Seville), Mauiricio Rodriguez-Ramos (Department of Atomic, Molecular and Nuclear Physics, Faculty of Physics, University of Seville), Lucia Sanchis-Sanchez (Department of Atomic, Molecular and Nuclear Physics, Faculty of Physics, University of Seville), Jaime Dominguez-Abascal (Department of Mechanical and Manufacturing Engineering, University of Seville)
• 10:46
2.28 Distribution of collected target debris using the Large Area Solid Debris Radiochemistry Collector 2h

The Large Area Solid Radiochemistry (LASR) collector was deployed at the National Ignition Facility (NIF) in 2017 to collect solid debris samples from NIF targets. The collector was a 20-cm vanadium foil (active area) fielded 50 cm from the NIF target chamber center. The foil was surrounded by a side enclosure, which was covered by an aluminum foil. After a shot, the vanadium and aluminum foils were removed and processed individually via radiation counting. The collector has applications for measuring nuclear data using the NIF capsule as an intense neutron source. LASR was fielded on two shots, both of which had a monolayer of 238U embedded in the capsule ablator 10 um from the inner surface. Fission and activation products produced via the interaction of 14-MeV fusion neutrons and 238U were collected using LASR. Subsequent analysis via gamma spectroscopy indicated that the distribution of fission products was not uniform, and the aluminum side foil collected more low- and high-mass wing fission products compared to the vanadium surface, which was enriched in peak and valley fission products. The results from these shots will be used to better design future nuclear data experiments at NIF.

Speakers: John Despotopulos (Lawrence Livermore National Lab), Dawn Shaughnessy (Lawrence Livermore National Lab), Narek Gharibyan (Lawrence Livermore National Lab), Kenton Moody (Lawrence Livermore National Lab), Patrick Grant (Lawrence Livermore National Lab), Charles Yeamans (Lawrence Livermore National Lab), Cory Waltz (Lawrence Livermore National Lab)
• 10:46
2.29 Unabsorbed Light Beamlets for Diagnosing Cross-Beam Energy Transfer 2h

A diagnostic has been fielded on OMEGA to diagnose cross-beam energy transfer (CBET) during implosions. Unabsorbed light from each laser beam is imaged as a “spot” in time-integrated images. Each spot is the end point of a beamlet that originates from a beam profile and follows a path determined by refraction. The intensity varies along that path as a result of absorption and CBET. This diagnostic allows for the investigation of the effects of CBET on laser energy from specific locations of the beam profile. The diagnostic records images in two time windows with each beamlet split into two orthogonal polarizations recorded on separate images, making it possible to determine the absolute polarization of each beamlet. When each beam is linearly polarized, CBET rotates the polarization of each beamlet. This diagnostic has provided the first evidence of polarization rotation caused by CBET during direct-drive implosions. A fully 3-D CBET hydrodynamics code postprocessor models the intensity, wavelength, and polarization of each beamlet along its path. The predicted images are compared to the images recorded by the new diagnostic. This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0001944.

Speakers: Dana Edgell (Laboratory for Laser Energetics, University of Rochester), Russell Follett (Laboratory for Laser Energetics, University of Rochester), Joseph Katz (Laboratory for Laser Energetics, University of Rochester), John Shaw (Laboratory for Laser Energetics, University of Rochester), David Turnbull (Laboratory for Laser Energetics, University of Rochester), Dustin Froula (Laboratory for Laser Energetics, University of Rochester)
• 10:46
2.30 The Dilation Aided Single-Line-of-Sight Camera for the National Ignition Facility, Characterization and Fielding 2h

Crystal x-ray imaging is frequently used in inertial confinement fusion and laser-plasma interaction applications, as it has advantages compared to pinhole imaging, such as higher signal throughput, better achievable spatial resolution and chromatic selection. However, currently used x-ray detectors are only able to obtain a single time resolved image per crystal. The dilation aided single-line-of-sight x-ray camera described here, designed for the National Ignition Facility (NIF) combines two recent diagnostic developments, the pulse dilation principle used in the dilation x-ray imager (DIXI) and a ns-scale multi-frame camera that uses a hold-and-readout circuit for each pixel (hCMOS). This enables multiple images to be taken from a single-line-of-sight with high spatial and temporal resolution. At the moment, the instrument can record two single-line-of-sight images with spatial and temporal resolution of 35 µm and down to 35 ps, respectively, with a planned upgrade doubling the number of images to four. Here we present the dilation aided single-line-of-sight camera for the NIF, including the x-ray characterization measurements obtained at the COMET laser and the results from the initial timing shot on the NIF. Prepared by LLNL under Contract DE-AC52-07NA27344. LLNL-ABS-7439

Speakers: Sabrina R. Nagel (Lawrence Livermore National Laboratory), A. C. Carpenter (Lawrence Livermore National Laboratory), J. Park (Lawrence Livermore National Laboratory), M. S. Dayton (Lawrence Livermore National Laboratory), P. M. Bell (Lawrence Livermore National Laboratory), D. K. Bradley (Lawrence Livermore National Laboratory), B. T. Funsten (Lawrence Livermore National Laboratory), B. W. Hatch (Lawrence Livermore National Laboratory), S. Heerey (Lawrence Livermore National Laboratory), J. M. Hill (Lawrence Livermore National Laboratory), J. P. Holder (Lawrence Livermore National Laboratory), E. R. Hurd (Lawrence Livermore National Laboratory), C. C. Macaraeg (Lawrence Livermore National Laboratory), P. B. Patel (Lawrence Livermore National Laboratory), R. B. Petre (Lawrence Livermore National Laboratory), K. Piston (Lawrence Livermore National Laboratory), C. A. Trosseille (Lawrence Livermore National Laboratory), K. Engelhorn (General Atomics), T. J. Hilsabeck (General Atomics), T. M. Chung (TMC2 Innovations LLC), A. K. L. Dymoke-Bradshaw (Kentech Instruments Ltd), J. D. Hares (Kentech Instruments Ltd), L. D. Claus (Sandia National Laboratories), T. D. England (Sandia National Laboratories), B. B. Mitchell (Sandia National Laboratories), J. L. Porter (Sandia National Laboratories), G. Robertson (Sandia National Laboratories), M. O. Sanchez (Sandia National Laboratories)
• 10:46
2.31 Development of an Electrostatic Dust Injector for Impurity Injection in Tokamak Plasmas 2h

Impurity injection can be a critical tool for studying impurity transport as well as in understanding physics of plasma-wall interactions in magnetic fusion. Impurity injection can also enable important diagnostic approaches such as spectroscopy and CHERS. While the speed limitations on gas injection and pellet injection are well known, electrostatic and electromagnetic injectors can overcome such limits and can in principle deliver impurity content in the km/s range. With this in mind, we have begun development of a high-voltage electrostatic dust injector, capable of launching large quantities of small (< 0.1 mm) particles to high speeds (>>100 m/s). This injector is an evolution of a design currently in use at the Univ. Colorado Dust Accelerator, a facility for planetary science and cosmic dust studies. The dust injector consists of a dust reservoir, a HV needle (or collection of needles), and a series of exit apertures. The reservoir holds approximately 1g of dust, and the apparatus is pulsed to 20 kV to charge and launch the particles. Studies are underway to maximize the mass flux achievable in such a design, through the optimization of the reservoir, needle, and aperture geometries, as well as the size distribution of the dust particles and the waveforms of the pulsed HV.

Speakers: Tobin Munsat (University of Colorado), Zhehui Wang (Los Alamos National Lab), John Fontanese (University of Colorado)
• 10:46
2.32 Polarization-splitting crystals for 2–30 keV spectral lines 2h

Certain crystal types have internal planes oriented such that they can be used as polarizing beam splitters at specific x-ray energies. Such a crystal can be used, for example, to measure the polarization of the spectral lines emitted by high-temperature plasmas. Generally, the polarization is caused by plasma anisotropy, and measuring it can provide insight into the mechanism that creates the anisotropy. Polarization measurements are possible using crystal planes with lattice spacing such that d√2 is close to the line wavelength, which ensures that the Bragg angle is in the vicinity of the perfectly polarizing 45°. The results of a systematic search for pairs of crystal planes and spectral lines that satisfy this polarization-splitting condition will be presented. The goal is to develop an instrument to measure and record simultaneous S and P polarizations of emitted x-rays in the 2–30 keV spectrum. This work was done by National Security Technologies, LLC, under Contract No. DE-AC52-06NA25946, by Mission Support and Test Services, LLC, under Contract No. DE-NA0003624, and by Sandia National Laboratories under contract DE-NA-0003525 with the U.S. Department of Energy, and supported by the Site-Directed Research and Development Program. DOE/NV/03624--0021

Speakers: R. Presura (Nevada National Security Site, New Mexico Operations), K. Moy (Nevada National Security Site, Special Technologies Laboratory), M. Wu (Sandia National Laboratories), C. Kruschwitz (Nevada National Security Site, New Mexico Operations), D. Ampleford (Sandia National Laboratories)
• 10:46
2.33 Performance of a Cauchois Geometry Spectrometer at the National Ignition Facility 2h

The NIF Survey Spectrometer (NSS) which uses the Cauchois geometry has been installed on the Nation Ignition Facility. The NSS is used to measure and L-shell emission from Au Holhraums and K-shell emission from mid to high Z elements from backlighters and bright x-ray sources. The NSS is mounted on a port at the bottom of the chamber with a line of sight that is 37° from vertical. This location allows an unobstructed view of the various x-ray sources and into the laser entrance hole of Hohlraums. The spectrometer has four separate crystal channels that can be reconfigured as required. Currently, quartz transmission crystals with 2d = 8.512, 6.684, 2.750 and 1.624 Å are available. Emission from 6.5 to a few 100 keV can be measured with significant spectral overlap between each crystal channel. The dispersion has been calculated for the NIF geometry and agrees with the location of several filter K-edges routinely fielded in the filter packs. The resolution of the instrument is ~ 140 in first order at E(photon) = 13 keV. Instrument details, first light results and initial performance will be presented. This work was done under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

Speakers: Mark May (Lawrence Livermore National Laboratory), Daniel Thorn (Lawrence Livermore National Laboratory), John Seely (Artep), Uri Feldman (Artep), Shannon Ayers (Lawrence Livermore National Laboratory), Nathaniel Thompson (Lawrence Livermore National Laboratory), Patrick Poole (Lawrence Livermore National Laboratory), Klaus Widmann (Lawrence Livermore National Laboratory), Gregory Kemp (Lawrence Livermore National Laboratory), Marilyn Schneider (Lawrence Livermore National Laboratory), Brent Blue (Lawrence Livermore National Laboratory)
• 10:46
2.34 Geometric fractionation of the NIF hohlraum debris 2h

Inertial confinement fusion experiments at NIF utilize a hohlraum, consisting of materials such as gold, uranium, aluminum and/or copper, that can provide potential diagnostic information when coupled with high-yield deuterium-tritium fueled shots. During such experiments, mega-joules of laser energy delivered inside the hohlraum results in its complete destruction and distribution of the material masses inside the target chamber. The collection and analysis of the scattered hohlraum debris are critical for the development of diagnostic capabilities. Previous diagnostics, such as Solid Radiochemistry (SRC), have relied on the collection of hohlraum debris by deploying large solid-angle collector systems to ensure sufficient amount of the hohlraum material was collected for providing a high-fidelity diagnostic measurement. In an effort to better understand the hohlraum debris distribution, we have performed several experiments at NIF where known amounts of various materials were mounted to the hohlraum. Results from these experiments, which will be presented in detail, indicate a strong geometric behavior of the post-shot hohlraum debris distribution.

Speakers: Narek Gharibyan (Lawrence Livermore National Laboratory), Dawn Shaughnessy (Lawrence Livermore National Laboratory), Ken Moody (Lawrence Livermore National Laboratory), Pat Grant (Lawrence Livermore National Laboratory), Charles Yeamans (Lawrence Livermore National Laboratory), John Despotopulos (Lawrence Livermore National Laboratory)
• 10:46
2.35 Initial Beam Emission Spectroscopy diagnostic system on the HL-2A tokamak 2h

A Beam Emission Spectroscopy system is being developed and deployed at the HL-2A tokamak to measure local low wavenumber (k_⊥ ρ_I<1) density fluctuations by observing Doppler-shifted emission from a 50 kV deuterium heating neutral beam. High spatial resolution (∆r≤1cm,∆z≤1.5cm) measurements are obtained with a 2 MHz sampling rate. An f/1.6, f=280 mm radiation-resistant in-vacuum objective lens couples with an off-axis field lens to image the beam to a curved surface with an appropriate angle for coupling to optical fibers. A 2x3 bundle of 1-mm diameter, 10-meter fibers conveys light for each spatial channel to detector arrays. A collimating lens passes light to a 1-nm bandwidth (659.2-660.2 nm, Doppler-shifted D-alpha emission) interference filter. An aspheric lens focuses light to a 2.65 mm square photodiode. High frequency, high-gain, low-noise preamplifiers sample the light intensity at a Nyquist frequency of 1 MHz with a high S/N ratio. A first set of 16 detector channels (12 plasma observing channels, configured in a 6(radial) x 2(poloidal) array) were installed and tested at HL-2A, covering the radial zone r/a=0.7~1.05. The frequency and wavenumber spectra have been measured during various plasma conditions, and primary measurements will be presented.

Speakers: Yifan Wu (University of Science and Technology of China), Rui Ke (Tsinghua University), Kurt Jaehnig (University of Wisconsin-Madison), Matt Kriete (University of Wisconsin-Madison), George McKee (University of Wisconsin-Madison), Zheng Yan (University of Wisconsin-Madison), Ting Wu (Southwestern of Institute of Physics), Min Xu (Southwestern of Institute of Physics)
• 10:46
2.36 A multi-species powder dropper for magnetic fusion applications 2h

Injection of solid powders has been used in fusion research for various applications, including wall conditioning and pedestal control. Due to the physical properties of various materials, typically, a powder injector is designed and optimized to handle a specific kind of powder. We present a device for controlled injection of a variety of materials in form of powder. The system implements four independent feeder units, arranged as to share a vertical drop tube. Each unit consists of a 30 ml reservoir, coupled to a horizontal linear pad, where a layer of powder is advanced by piezo-electric agitation at a speed proportional to the applied voltage, until it falls into the drop tube. The dropper has been tested with a range impurities of low (B, BN, C), intermediate (Si, SiC) and high Z (Sn) and a variety of microscopic structures (flakes, spheres, rocks) and sizes (5-100 um). For low Z materials (e.g. B, BN), drop rates ~2-200 mg/s have been obtained with excellent linearity, repeatability and uniformity. A calibrated LED-based flow-meter allows measuring and monitoring the drop rate during operation. The fast-response of the four feeders allows combining long duration and pulsed injections, providing a flexible tool for controlled-dose impurity injection in fusion plasmas.

Speaker: Alessandro Bortolon (Princeton Plasma Physics Laboratory)
• 10:46
2.37 The NIF backscatter system: current capabilities and planned improvements 2h

Recent indirect drive hohlraum designs for ignition targets on the National Ignition Factify (NIF) are exploring higher laser energy (~ 2 MJ) and power (500 TW) as a way of increasing neutron yield. A consequence is increased laser-plasma interactions (LPI), resulting in increased hot-electrons and cross-beam transfer that moves laser power between laser cones and backscatter in the form of stimulated Brillouin and stimulated Raman scattering (SBS and SRS). Accurate measurement of the backscattered light can give insight into the hohlraum plasma conditions and help quantify the amount of energy that is coupled into the hohlraum. Backscattered light is currently measured at NIF using a full aperture backscatter system (FABS) and near backscatter imager (NBI) instrument. Both diagnostics work in synergy to measure the backscattered energy, power, and temporal spectra evolution. In this work, we will present the current status of these diagnostics and discuss future improvements that will lead to more accurate results. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under the contract DE-AC52-07NA27344. Lawrence Livermore National Security, LLC. LLNL-ABS-744433.

Speakers: Nuno Lemos (Lawrence Livermore National Laboratory), J Park (Lawrence Livermore National Laboratory), J. S Ross (Lawrence Livermore National Laboratory), G Sawdling (Lawrence Livermore National Laboratory), P Michel (Lawrence Livermore National Laboratory), C Goyon (Lawrence Livermore National Laboratory), L Divol (Lawrence Livermore National Laboratory), N Butler (Lawrence Livermore National Laboratory), J. D. Moody (Lawrence Livermore National Laboratory)
• 10:46
2.38 Average neutron time-of-flight instrument response function inferred from single D-T neutron events within a plastic scintillator 2h

The bulk ion-temperature and neutron reaction history are important characteristics of a fusion plasma. Extracting these from a measured neutron-time-of-flight (nTOF) signal, either by convolution or de-convolution methods, requires accurate knowledge of the instrument response function (IRF). This work describes a novel method for obtaining the IRF directly for single D-T neutron interactions by utilizing n-alpha coincidence. The t(d, α)n nuclear reaction was produced at Sandia National Laboratories' Ion Beam Laboratory using a 300-keV Cockcroft-Walton generator to accelerate a 2-μA beam of 175-keV D+ ions into a stationary ErT2 target. The average neutron IRF was calculated by taking a time-corrected average of individual neutron events within an EJ-228 plastic scintillator. The scintillator was independently coupled to two photo-multiplier tubes operated in current-mode: a Hamamatsu 5928 mod-5 and a Photek PM240. The experimental set-up and experimental results will be discussed.Work supported by DOE NNSA contract DE-NA0003525.

Speakers: Jedediah Styron (University of New Mexico, Nuclear Engineering), Carlos Ruiz (Sandia National Laboratories), Kelly Hahn (Sandia National Laboratories), Gary Cooper (University of New Mexico, Nuclear Engineering), Gordon Chandler (Sandia National Laboratories), Brent Jones (Sandia National Laboratories), Bruce McWatters (Sandia National Laboratories), Jeremy Vaughan (University of New Mexico, Nuclear Engineering), Jose Torres (Sandia National Laboratories), Perry Alberto (Sandia National Laboratories)
• 10:46
2.39 Radiation diagnostics for plasma current ramp-up and ramp-down research 2h

The plasma current ramp-up and ramp-down that are always along with strong instabilities are the unavoidable processes in the tokamak operation. In order to research these processes in SUNIST(Sino-UNIted Spherical Tokamak), some diagnostic systems that detect the plasma radiation ranging from hard X-rays to visible light are developed. CdZnTe and Silicon drift detectors measure the energy spectrum of hard X-rays and soft X-rays coming from different positions of the plasma. A pinhole camera equipped with an AXUV-16ELG array photodiodes has been installed on the top of SUNIST to observe the radiation power loss and the MHD activities with high temporal and spatial resolution. The spectrum of vacuum ultraviolet is acquired by CCD camera and the intensity of some lines can be measured by PMT with scintillator. The full spectrum of the visible light can be acquired in every 3ms, and the intensity of some lines, such as H_α, H_β can be measured by filter scopes with high time response. Additionally, a Doppler broadening measurement system is developed to measure the ion temperature of edge plasma.

Speakers: Binbin Wang (Tsinghua University), Yi Tan (Tsinghua University), Zhe Gao (Tsinghua University), Shouzhi Wang (Tsinghua University)
• 10:46
2.40 Multiple nuclear burn history measurements using Cherenkov γ-ray detectors 2h

Thermonuclear burn history measurements are an important diagnostic of inertial fusion implosion performance, with several instruments developed based on the Cherenkov technique. Depending on the target composition and fuel, several nuclear reactions can produce g rays at different energies. We present a new technique that uses multiple detectors, with varied thresholds, to simultaneously measure multiple -ray burn histories with high relative precision. The first application of this technique has been to measure both DT and HT burn from deuterated plastic shell targets filled with H2+T2 gas and imploded on the OMEGA laser facility. These data will constrain models of material mixing from the shell into the fuel, and kinetic phenomena in implosions. Future applications, including measurements at the NIF, will be discussed.

Speakers: Alex Zylstra (LANL), Hans Herrmann (LANL), Yongho Kim (LANL), Mark Schmitt (LANL), Nelson Hoffman (LANL), Aaron McEvoy (LANL), Gerry Hale (LANL), Kevin Meaney (LANL), Hermann Geppert-Kleinrath (LANL), Alex Leatherland (AWE), Steven Gales (AWE), Vladimir Glebov (LLE), Chad Forrest (LLE), Christian Stoeckl (LLE)
• 10:46
2.41 Commissioning and Calibration of VUV Spectrometer on Versatile Experiment Spherical Torus 2h

A vacuum ultraviolet (VUV) spectrometer spanning wavelength range 5-20 nm was commissioned on Versatile Experiment Spherical Torus (VEST), and wavelength calibration was conducted. The incident lights at 87° diffract at the 1200 g/mm concave grating and form a spectral image on the flat focal plane. A back-illuminated charge coupled device (CCD) of 2048 x 512 pixel array (13.5 x 13.5 μm2/pixel) observes the temporal evolution of spectrum during VEST discharge. A spectrum of oxygen and carbon impurity lines of VEST is predicted by OPEN-ADAS database and NIST database, and the wavelength calibration is carried out by the obtained spectrum and the wavelength positions on the flat-field focal plane. The electron density and temperature of VEST is estimated by comparing the ratio of the measured peaks with the predicted spectrum of carbon and oxygen in VEST using collisional radiative (CR) model and OPEN-ADAS database.

Speakers: Jongin Wang (Seoul National University), J.H Kim (Seoul National University), Kyoung-Jae Chung (Seoul National University), Y.S. Hwang (Seoul National University)
• 10:46
2.42 Upgrades to the electron cyclotron emission diagnostic in KSTAR 2h

The electron cyclotron emission (ECE) diagnostic system with a 48 channel D-band heterodyne radiometer has been routinely used to measure the electron temperature as well as its radial profile on the Korea Superconducting Tokamak Advanced Research (KSTAR) tokamak. However, because the overlap between the second and the third harmonic emission frequencies on the high-field side at 2.0 T is not avoidable, a 28 channel W-band heterodyne radiometer has been added to measure the electron temperature on the low-field side. As main components of a new radiometer, a 94 GHz local oscillator, two double-balanced mixers, and two bandpass filters (78-93 GHz and 95-110 GHz) are used to obtain two separate IF signals (1–16 GHz). Subsequently two sets of second down-conversion modules with a 7 GHz local source and 4 sets of 8 channel detector modules (2-9 GHz) with 1 GHz step are used. In this article, an overview of the upgraded ECE system and preliminary ECE measurements are presented.

Speakers: KYU-DONG LEE (National Fusion Research Institute), YONG-SEON KIM (National Fusion Research Institute)
• 10:46
2.43 Systematic study of turbulence properties through reflectometry spectra 2h

Turbulence is an important issue in fusion plasmas as it was found to have a direct link to the particles and heat transports, and hence the confinement performance. In this paper, we report on a turbulence database that was built from measurements of Tore Supra core reflectometer [1] by parametrization of density fluctuation frequency spectra [2], including 350,000 spectra from 6,000 discharges, covering the global and local parameters.The characteristics of the broad band (BB) component of the spectra will be presented. In Ohmic plasmas, the reduction of the BB component in the central region is linked to the q=1 surface. In linear Ohmic confinement (LOC) regime, the BB component amplitude inside this basin is lower than in the saturated Ohmic confinement (SOC) regime. This basin might be explained by a drop of turbulence level inside q=1 surface. It disappears with increasing ICRH power. The shape of the BB component which is Gaussian on the outer side becomes triangular or Lorentzian on the inner side. This shape modification might be related to a modification of the turbulence structure.References [1] R. Sabot et al., Nucl. Fusion 46, S685-S692 (2006) [2] Y. Sun et al., the 13th international reflectometry workshop proceedings (2017)

Speakers: Yan Sun (IRFM, CEA Cadarache), Roland Sabot (IRFM, CEA Cadarache), Stéphane Heuraux Stéphane (Université de Lorraine), Geert Verdoolaege (Ghent University ), Sébastien Hacquin (IRFM, CEA Cadarache), Grégiore Hornung (Ghent University )
• 10:46
2.44 Coherence imaging system for 2D distribution of ion temperature and flow velocity in laboratory magnetosphere 2h

Coherence imaging (CI) system has been developed to investigate the mechanism of the high-beta plasma formation in a laboratory magnetosphere and plasma particle transport that creates self-organization. The CI system is possible to measure 2D profile of ion temperature and flow velocity in RT-1 magnetospheric plasmas. The CI system utilizes the optical interference by a birefringent crystal instead of the dispersion by a grating. A CMOS image sensor captures an interferogram of He+ line (468 nm). Performing a fast Fourier transform on the interferogram extracts the intensity, the contrast, and the phase shift at each point, we can introduce the ion temperature and flow velocity from the quantities of the fringe contrast and phase with an instrumental phase, respectively. We successfully observed the 2D distribution of ion temperature in the magnetospheric plasma.

Speakers: Kaori NAKAMURA (Graduate School of Frontier Sciences, The University of Tokyo), Masaki NISHIURA (Graduate School of Frontier Sciences, The University of Tokyo), Noriki TAKAHASHI (Graduate School of Frontier Sciences, The University of Tokyo), Zensho YOSHIDA (Graduate School of Frontier Sciences, The University of Tokyo), Naoki KENMOCHI (Graduate School of Frontier Sciences, The University of Tokyo), Tetsuya SUGATA (Graduate School of Frontier Sciences, The University of Tokyo), Shotaro KATSURA (Graduate School of Frontier Sciences, The University of Tokyo), John HOWARD (The Australian National University), Clive MICHAEL (The Australian National University)
• 10:46
2.45 High magnetic field test of the ITER outer vessel steady-state magnetic field Hall sensors at ITER relevant temperatures 2h

The outer vessel steady-state magnetic field sensors constitute a part of the ITER magnetic diagnostics. The sensor set consists of a poloidal array of 60 sensors placed on the vacuum vessel outer skin and distributed toroidally in three vacuum vessel sectors. Each sensor unit features a pair of metallic Hall sensors with a sensing layer made of bismuth measuring tangential and normal components of the magnetic field. Before the installation on ITER, the sensors will be calibrated in the magnetic field of a few mT, whereas the magnetic field to be measured by the sensors in ITER is up to a few T. A characteristic feature of the bismuth Hall sensors, found in earlier experiments, is the Hall coefficient exponential dependence on temperature and Gaussian dependence on the magnetic field. In the new experiment, the sensors were tested at magnetic field ranging from -12 T to +12 T and ITER relevant temperatures from room temperature to 130 °C, and the two-dimensional non-linear bismuth Hall coefficient function of temperature and magnetic field was found. These results allow constructing a model for the correct interpretation of the sensor calibration.

Speakers: Slavomir Entler (Institute of Plasma Physics of the CAS), Josef Sebek (JLMS Institute of Physics of the CAS), Ivan Duran (Institute of Plasma Physics of the CAS), Martin Kocan (ITER Organization), George Vayakis (ITER Organization)
• 10:46
2.46 Neutron measurements at the ELISE neutral beam test facility and implications for neutron based diagnostics at SPIDER 2h

Along the route to the development of a neutral beam injector for ITER, the Padua based SPIDER and MITICA facilities will make use of neutron diagnostics to quantify the homogeneity of the neutral beam profile by measurements of the map of the neutron emission from the beam dump with ad hoc developed Gas Electron Multipliers (GEM). Neutrons are here born from beam target reactions between the beam and the deuterium ions previously adsorbed in the dump. In order to aid the interpretation of the diagnostic data, we have used the ELISE neutral beam test facility for a dedicated experiment on neutron emission from beam-target reactions in a range of parameters approaching that of SPIDER. A calibrated liquid scintillator detector has been employed to monitor neutron emission from a defocused beam and at increasing power densities on the dump. Compared to calculations based on the so called “local mixing model”, the experimental results show a discrepancy exceeding the statistical accuracy of the measurements and which increases as a function of the power density. The data are used to derive an empirical correction for applications to neutron measurements at SPIDER, where a liquid scintillator detector is now planned for installation as a monitor to complement the main GEM diagnostics.

Speakers: Song Feng (University of Milano-Bicocca), Massimo Nocente (University of Milano-Bicocca), Dirk Wuenderlich (Max Planck Institute for Plasma Physics), Federica Bonomo (Max Planck Institute for Plasma Physics), Gabriele Croci (University of Milano-Bicocca), Ursel Fantz (Max Planck Institute for Plasma Physics), Bernd Heinemann (Max Planck Institute for Plasma Physics), Werner Kraus (Max Planck Institute for Plasma Physics), Isabella Mario (Max Planck Institute for Plasma Physics), Andrea Muraro (Institute of Plasma Physics, National Research Council), Roberto Pasqualotto (Consorzio RFX), Marica Rebai (Institute of Plasma Physics, National Research Council), Marco Tardocchi (Institute of Plasma Physics, National Research Council), Giuseppe Gorini (University of Milano-Bicocca)
• 10:46
2.47 High-Speed Visible Image Diagnostics System for Real-time Plasma Boundary Reconstruction of EAST Tokamak 2h

Fast plasma boundary reconstruction is usually used for real-time control of tokamak plasma. In EAST experiment, the time consuming for boundary reconstruction should be within 1ms to meet the need of real-time control. Fast evolution of cameras in recent years has made them promising tools for diagnostics of Tokamak. The solution presented in this paper consists of a prototype of high-speed visible image acquisition and processing system(HVIAPs) dedicated for EAST tokamak shape and position control. Using the compute unified device architecture (CUDA) framework, a GPU and FPGA based parallel algorithm for plasma boundary reconstruction with visible imaging diagnostics is developed. Compared to the reconstruction of EFIT, the average error is 1.5cm. In particular, the parallelization of the visible image plasma boundary reconstruction for the NVIDIA Quadro GP100 can complete calculation within 0.3ms, achieving the speedup of 14 and 90 for an image size of 544×680, when compared with parallel C with OpenMP extensions and parallel MATLAB. Furthermore, when the camera sensor is not saturated, the algorithm is robust for different intensities of the plasma discharge image.

Speakers: Heng Zhang (Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, China), Bingjia Xiao (Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, China), Zhengping Luo (Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, China), Qin Hang (Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, China)
• 10:46
2.48 High-Resolving-Power, Streaked X-Ray Spectroscopy on the OMEGA EP Laser System 2h

A high-resolving-power, streaked x-ray spectrometer is being developed and tested on the OMEGA EP Laser System to study temperature-equilibration dynamics in rapidly heated metal. The instrument is based on two diagnostic channels, each with a spherical Bragg crystal. Channel 1 couples a spherical Si220 crystal to an x-ray streak camera. Channel 2 couples a second, identical crystal to an x-ray charge-coupled device (CCD), allowing for photometric calibration of the time-resolved spectrum. The instrument covers the spectral range of 7.97 to 8.11 keV, centered on the Cu Ka1 line at 8.05 keV. The time-resolved spectrometer is designed to achieve a resolving power of 2000 and a temporal resolution of 2 ps. The instrument capabilities are demonstrated by resolving the Cu Ka1,2 doublet on high-power shots. Time-resolved Cu Kα spectra for a wide range of high-power laser and target interactions, where heating and Kα emission is generated by hot-electron-energy deposition, will be presented. This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0001944.

Speakers: Philip Nilson (Laboratory for Laser Energetics), Frank Ehrne (Laboratory for Laser Energetics), Cody Taylor (Laboratory for Laser Energetics), Chad Mileham (Laboratory for Laser Energetics), Dino Mastrosimone (Laboratory for Laser Energetics), Robert Jungquist (Laboratory for Laser Energetics), Robert Boni (Laboratory for Laser Energetics), Jeremy Hassett (Laboratory for Laser Energetics), Collin Stillman (Laboratory for Laser Energetics), Steven Ivancic (Laboratory for Laser Energetics), Dave Lonobile (Laboratory for Laser Energetics), Richard Kidder (Laboratory for Laser Energetics), Milt Shoup (Laboratory for Laser Energetics), Andrey Solodov (Laboratory for Laser Energetics), Adam Sefkow (Laboratory for Laser Energetics), Christian Stoeckl (Laboratory for Laser Energetics), Wolfgang Theobald (Laboratory for Laser Energetics), Dustin Froula (Laboratory for Laser Energetics), Ken Hill (Princeton Plasma Physics Laboratory), Lan Gao (Princeton Plasma Physics Laboratory), Manfred Bitter (Princeton Plasma Physics Laboratory), Philip Efthimion (Princeton Plasma Physics Laboratory), David` Meyerhofer (Los Alamos National Laboratory)
• 10:46
2.49 Research on the normal spectral band emissivity of tungsten between 150 and 500°C 2h

Tungsten is an important alternative material to construct the divertor for Tokamak. Due to the effect of the interaction of plasma and the first wall, the first wall, especially the divertor area, will bear high energy to act on the area. Therefore, the detection and diagnosis of the first wall temperature of Tokamak by non-contact temperature measurement is the premise to ensure the safe and stable operation of the whole facility. However, in order to achieve high precision non-contact temperature measurement, we must accurately measure the emissivity of tungsten. In this paper, we built a set of emissivity measurement system and a new method for accurate calculation of emissivity is proposed. This method effectively eliminated the interference of background radiation and improves the accuracy of emissivity measurement. By using this method, the author measured the emissivity of tungsten under the conditions of different surface roughness in the range of 150°C to 500°C, and discussed the uncertainty of the experiment at the end.

Speakers: Yan Zhang (School of Instrument Science and Opto-electronics Engineering of Hefei University of Technology), Yuzhong Zhang (School of Instrument Science and Opto-electronics Engineering, Hefei University of Technology), Shuangbao Shu (School of Instrument Science and Opto-electronics Engineering, Hefei University of Technology), Rongsheng Lu (School of Instrument Science and Opto-electronics Engineering, Hefei University of Technology), Xianli Lang (School of Instrument Science and Opto-electronics Engineering, Hefei University of Technology)
• 10:46
2.50 Title of Abstract: Application of Portable Near-Infrared Spectrometer to Heliotron J Plasmas 2h

A Simple near-infrared (NIR) spectrometer for 898 - 2130 nm has recently been applied to Heliotron J plasmas. It adopts symmetrical crossed Czerny-Turner mount equipped with a thermoelectrically cooled 512 channel InGaAs linear sensor. Reciprocal linear dispersion was deduced as 96.37 nm/mm at the center of the detector. Several types of the 2nd order rejection filter are inserted in the collection optics as needed. Calibration was performed together with a visible spectrometer using a tungsten halogen lamp and the result was compared with the intensity ratio of the Paschen α (1875 nm) and Balmer β (486 nm) lines, both of which have a common upper quantum level. The purpose of this study includes extending the wavelength region of the spectral monitor to less contaminated region. In the preliminary measurements, we observed the Paschen series for the hydrogen pellet injection plasma and two atomic helium lines, i.e. 2S-2P singlet and triplet lines, for Helium gas puffing experiments. A Continuum spectrum in this regime is entirely attributable to the blackbody radiation from the heat spots on the plasma-facing components. In addition, this may also be used to monitor if there are any significant background radiation in the YAG Thomson scattering signals near 1064 nm.

Speakers: Shinichiro Kado (Institute of Advanced Energy, Kyoto University ), Akihiro Iwata (Graduate School of Energy Science, Kyoto University), Tomomi Kanazawa (Graduate School of Energy Science, Kyoto University ), Hiroyuki Okada (Institute of Advanced Energy, Kyoto University), Satoshi Yamamoto (Institute of Advanced Energy, Kyoto University), Gen Motojima (National Institute for Fusion Science), Hisashi Okazaki (Graduate School of Energy Science, Kyoto University), Takashi Minami (Institute of Advanced Energy, Kyoto University), Shinji Kobayashi (Institute of Advanced Energy, Kyoto University), Kazunobu Nagasaki (Institute of Advanced Energy, Kyoto University), Shinsuke Ohshima (Institute of Advanced Energy, Kyoto University), Yuji Nakamura (Graduate School of Energy Science, Kyoto University), Akihiro Ishizawa (Graduate School of Energy Science, Kyoto University), Shigeru Konoshima (Institute of Advanced Energy, Kyoto University), Toru Mizuchi (Institute of Advanced Energy, Kyoto University)
• 10:46
2.51 Design and Raytrace Simulations of a Multilayer-Coated Wolter X-Ray Optic for SNL’s Z Machine 2h

Recent breakthroughs in the fabrication of small-radii Wolter optics allow NNSA facilities to consider such optics as x-ray diagnostics at 15-50 keV. Recently, LLNL, SNL, the Harvard-Smithsonian Center for Astrophysics and NASA MSFC jointly developed and fabricated the first custom Wolter microscope for implementation in SNL’s Z machine with optimized sensitivity at 17.4 keV. To achieve spatial resolution of order 100-200 microns over 5x5x5 mm3 with high throughput and narrow energy bandpass, the geometry of the optic and its multilayer (ML) required careful design and optimization. While the geometry mainly influences resolution and field of view, the mirror coating determines spectral response and throughput. Here we outline the details of the design process for the first Z Wolter including the optimization of its WSi ML and present results of raytrace simulations completed to predict and verify the performance of the optic. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. Sandia National Laboratories is a multimission laboratory managed and operated by NTESS,LLC., a wholly owned subsidiary of Honeywell International,Inc., for the U.S. DOE's NNSA under contract DE-NA-0003525.

Speakers: Julia K. Vogel (LLNL), Michael J. Pivovaroff (LLNL), Bernard Kozioziemski (LLNL), Christopher C. Walton (LLNL), Jay Ayers (LLNL), Perry Bell (LLNL), Dave Bradley (LLNL), Marie-Anne Descalle (LLNL), Stefan Hau-Riege (LLNL), Louisa Pickworth (LLNL), David J. Ampleford (SNL), Christopher R. Ball (SNL), Chris J. Bourdon (SNL), Jeffrey R. Fein (SNL), A. J. Maurer (SNL), Ming Wu (SNL), Andrew Ames (Harvard-Smithsonian Center for Astrophysics), Ricardo J. Bruni (Harvard-Smithsonian Center for Astrophysics), Suzanne Romaine (Harvard-Smithsonian Center for Astrophysics), Oliver J. Roberts (Universities Space Research Association (USRA)), Kiranmayee Kilaru (Universities Space Research Association (USRA)), Brian Ramsey (NASA Marshall Space Flight Center), Brian Ramsey (NASA Marshall Space Flight Center)
• 10:46
2.52 Characterization of Shaped Bragg Crystal Assemblies for Narrowband X-Ray Imaging 2h

X-ray imaging using shaped crystals in Bragg reflection is a powerful technique used in high-energy-density physics experiments. The characterization of these crystal assemblies with conventional x-ray sources is very difficult because of the required angular resolution of the order of ~10 murad and the narrow bandwidth of the crystal. The 10-J, 1-ps Multi-Terawatt (MTW) laser at the Laboratory for Laser Energetics was used to characterize a set of Bragg crystal assemblies. The small spot size of the order of 10 mum and the high power (>10^18 W/cm^2) of this laser make it possible to measure the spatial resolution at the intended photon energy. A set of six crystals from two different vendors was checked on MTW, showing an unexpectedly large variation in spatial resolution of up to a factor of 4. This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0001944.

Speakers: Christian Stoeckl (LLE, University of Rochester), Tim Filkins (LLE, University of Rochester), Robert Junquist (LLE, University of Rochester), Chad Mileham (LLE, University of Rochester), Sean Regan (LLE, University of Rochester), Milton Shoup (LLE, University of Rochester), Wolfgang Theobald (LLE, University of Rochester)
• 10:46
2.53 Design of a Custom Insertable Probe Platform for Measurements of C-2W Inner Divertor Plasma Parameters 2h

A custom motor controlled probe system has been designed to make spatially resolved measurements of temperature, density, flow, and plasma potential in the C-2W inner divertors. Measurements in the inner divertors, which have a radius of 1.7 m and are located on either end of the confinement vessel, are critical in order to gauge exactly how local settings affect the plasma conditions, confinement, and stability in the FRC core. The inner Divertor Insertable Probe Platform (iDIPP) system consists of a custom motor controlled linear rack and pinion transporter that has a 1.9 m travel length in order to reach the center of the divertor. Mounted to the end of the transporter is a 1 m long segmented probe shaft made of individually floating stainless steel rings to prevent shorting out the electrode plates, which are biased up to 5 kV/m. A variety of interchangeable probe tips, including a triple Langmuir probe, a baffled probe, and a Gundestrup probe, can be easily plugged into the end of the probe shaft. Custom UHV coiled cabling comprised of 9 shielded conductors expands/retracts with the motion of the transporter in/out of the divertor. Details of the design of the iDIPP system and initial measurements of plasma parameters in the C-2W inner divertor will be discussed.

Speakers: Ami M. DuBois (TAE Technologies, Inc.), Vladimir Sokolov (TAE Technologies, Inc.), Kurt Knapp (TAE Technologies, Inc.), Matt C. Thompson (TAE Technologies, Inc.), The TAE Team (TAE Technologies, Inc.)
• 10:46
2.54 Optimizing neutron imaging lines of sight locations for maximum sampling of the cold fuel density in Inertial Confinement Fusion implosions at the National Ignition Facility 2h

Optimizing neutron imaging lines of sight locations for maximum sampling of the cold fuel density in Inertial Confinement Fusion implosions at the National Ignition Facility S. H. Batha, P. L Volegov, V. E. Fatherley, V. Geppert-Kleinmath, and C. A. Wilde Los Alamos National Laboratory Neutron imaging provides a ready measurement of the shape of the “hot spot” core of an inertial confinement fusion implosion. The 14-MeV neutrons emitted by deuterium-tritium reactions are imaged at the National Ignition Facility using a pinhole array onto a scintillator and the images are recorded on a camera. By changing the gate time of the camera lower energy neutrons, down scattered by the cold fuel surrounding the hot spot, are recorded. The cold fuel density can be reconstructed using the two images. The kinematics of the scattering, coupled with the scattering cross sections restrict the angular extent of the cold fuel sampled, with the backside of the implosion not being sampled at all. This work demonstrates the limited region of the cold fuel measured by the current line of sight and the new lines of sight being built. The locations of future lines of sight to provide full 4π coverage are also given.

Speakers: Steve Batha (LANL), Petr Volegov (LANL)
• 10:46
2.55 Non-Inductive Vertical Position Measurements by Faraday-effect Polarimetry On EAST tokamak 2h

The vertical position for elongated, long-pulse tokamak plasmas has to be precisely controlled to optimize performance and prevent disruptions. For a steady-state tokamak reactor, integration of voltage signals arising from flux change is extremely challenging due to zero-offset drift as the measurement is intrinsically inductive. The vertical position of the plasma core current density is defined as the position where radial magnetic field is zero, making this parameter critical to investigating vertical instability. A Faraday-effect POlarimeter-INTerferometer system has been developed for measuring the internal radial magnetic field in EAST. Horizontally-viewing chords at/near the midplane allow us to determine plasma vertical position non-inductively with sub-centimeter spatial resolution and 1 s time response. The polarimeter-based position measurement, which does not require equilibrium reconstruction, is benchmarked against conventional flux loop measurements for EAST discharges. Non-inductive vertical position measurements are very promising for future steady-state plasmas and fast time response allows for direct feedback on plasma vertical displacement instabilities. Work supported by US DOE through grants DE-FG02-01ER54615 and DC-SC0010469.

Speakers: WEIXING DING (University of California Los Angeles ), Jie Chen (University of California Los Angeles ), David Brower (University of California Los Angeles ), Haiqing Liu (Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, Anhui 230031, P.R. China), J.P. Qian (Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, Anhui 230031, P.R. China), Z.Y. Zou (Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, Anhui 230031, P.R. China), Y.X. Jie (Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, Anhui 230031, P.R. China), B.J. Xiao (Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, Anhui 230031, P.R. China), Z.P. Luo (Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, Anhui 230031, P.R. China), X.Z. Gong (Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, Anhui 230031, P.R. China), L.Q. HU (Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, Anhui 230031, P.R. China), B.N. Wan (Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, Anhui 230031, P.R. China)
• 10:46
2.56 High-Speed Solid-State X-ray Framing Camera Improvements and Performance Testing 2h

The Icarus sensor is the newest version of the hybrid-CMOS high-speed x-ray framing camera that has been under development at Sandia for over a decade. Icarus can store 4 images per pixel, has improved soft x-ray detection sensitivity, and an option to independently trigger each half of the sensor to effectively operate as two closely-spaced framing cameras with 1024x256 pixels each. Icarus maintains the 25µm pixel pitch, nearly 100% detector fill factor, and sub-2ns minimum integration time of our previous sensors: Griffin, Furi, and Hippogriff. We use a combination of pulsed visible and x-ray sources to measure the sensor performance. Results will be presented of gate time profiles for a variety of timing configurations, frame-to-frame cross talk, trigger jitter and insertion delay, spatial resolution, pixel response uniformity, dynamic range, and absolute x-ray sensitivity. We will also describe recent measurements of sensor performance when illuminated with multiple closely-spaced light pulses and with continuous illumination spanning multiple frames to determine effective on/off rejection ratios. Sandia is a multimission laboratory managed and operated by NTESS LLC, a wholly owned subsidiary of Honeywell Int., Inc., for the U.S. DOE’s NNSA under contract DE-NA0003525.

Speakers: Mark Kimmel (Sandia National Laboratories), Anthony Colombo (Sandia National Laboratories), Joel Long (Sandia National Laboratories), Quinn Looker (Sandia National Laboratories), John Stahoviak (Sandia National Laboratories), Liam Claus (Sandia National Laboratories), Troy England (Sandia National Laboratories), Lu Fang (Sandia National Laboratories), Brandon Mitchell (Sandia National Laboratories), Andrew Montoya (Sandia National Laboratories), Gideon Robertson (Sandia National Laboratories), Marcos Sanchez (Sandia National Laboratories), Greg Rochau (Sandia National Laboratories), John Porter (Sandia National Laboratories)
• 18:30 20:30
Session #3, Monday Night Invited Talks, Chair: C. Domier
• 18:30
3.1 Innovative diagnostic techniques for ICF on the ShenGuang-III laser facility in China 30m

Shenguang-III (SG-III) laser facility, developed by laser fusion research center (LFRC), is designed to provide the experimental capabilities to study the inertial confinement fusion (ICF) physics in China. The disintegrate experiments of inertial confinement fusion physics could be carried out at SG-III laser facility. Over 80 diagnostics have been installed at SG-III laser facility, including the optical diagnostics, the x-ray imaging diagnostics, the x-ray spectrum diagnostics, the fusion product diagnostics, the general diagnostics assistant systems, and the central control and data acquisition systems. In this presentation, we will introduce some new diagnostic techniques. These new diagnostic concepts and techniques which had been developed, included the full aperture backscattering system (FABS), near backscattering system (NBS), three dimensional velocity interferometer system for any reflector (3D-VISAR), optical Thomson scattering system (OTS), X-ray transition bandpass system (XTDS), eight channel Kirkpatrick-Baez mirror, spherical bent crystal system (SBS), spatial resolution flux diagnostic system (SRFD). The diagnostics platforms play important roles in the ICF experiments at SG-III laser facility.

Speaker: Feng Wang (Laser Fusion Research Center)
• 19:00
3.2 Inferring the distribution function from diagnostic measurements 30m

All the information about a plasma species is encoded in its distribution function (DF). While it would be helpful to measure the DF directly it is only possible to measure its moments. If the form of DF is not known a priori it can be difficult to interpret diagnostic signals. This is particularly true in fast-ion physics where, due to the complicated nature of the fast-ion DF, velocity-space weight functions were developed to interpret experimental data. Weight functions also allow for the inference of an approximate, spatially localized fast-ion DF i.e. Velocity-space Tomography. However, the technique is restricted, both by its accuracy and the availability of spatially overlapping diagnostics. In this work we overcome these limitations by extending velocity-space weight functions to a 3D orbit-space without loss of generality. We show how orbit weight functions can be used to infer the entire fast-ion DF from experimental data, i.e. Orbit Tomography. Using Fast-ion D-α (FIDA) data taken during a sawtooth crash at ASDEX-Upgrade, we show how Orbit Tomography can be used to do a first of its kind direct comparison between theoretical predictions and experimental measurements.This work was supported by the U.S. Department of Energy under DE-AC02-09CH11466 and DE-FC02-04ER54698

Speakers: Luke Stagner (University of California, Irvine), W.W. Heidbrink (University of California, Irvine), A.S. Jacobsen (Max Planck Institute for Plasma Physics), B. Geiger (Max Planck Institute for Plasma Physics), M. Weiland (Max Planck Institute for Plasma Physics), the DIII-D and ASDEX Upgrade Team
• 19:30
3.3 Active spectroscopy measurements of the deuterium temperature, rotation, and density from the core to scrape off layer on the DIII-D tokamak 30m

Main-ion charge exchange recombination spectroscopy (MICER) [1] uses the neutral beam induced D-alpha spectrum to measure local deuterium (D) temperature, rotation and density, plus neutral-beam parameters. An edge MICER system consisting of 16 densely packed chords was recently installed on DIII-D extending the MICER technique from the core to the pedestal and steep gradient region of H-mode plasmas where the D and commonly measured impurity properties can differ significantly. A combination of iterative collisional radiative modeling techniques and greatly accelerated spectral fitting algorithms allowed the extension of this diagnostic technique to the plasma edge where the steep gradients introduce significant diagnostic challenges. The system was operational for the 2017 DIII-D campaign and acquired data for a wide range of plasma conditions uncovering large temperature differences between D+ and impurities near the separatrix, inwardly shifted C6+ density pedestals, and strong co-Ip D edge rotation.The measurements and analysis demonstrate the state of the art in active spectroscopy and integrated modeling for diagnosing fusion plasmas and the importance of direct D measurements. [1]B. Grierson, RSI, 2012 Work supported by US DOE under DE-FC02-04ER54698 and DE-AC02-09CH11466

Speakers: Shaun Haskey (Princeton Plasma Physics Laboratory), Brian Grierson (Princeton Plasma Physics Laboratory), Colin Chrystal (General Atomics), Luke Stagner (University of California Irvine), Keith Burrell (General Atomics), Richard Groebner (General Atomics), David Kaplan (General Atomics), Novimir Pablant (Princeton Plasma Physics Laboratory), Arash Ashourvan (Princeton Plasma Physics Laboratory), Alessandro Bortolon (Princeton Plasma Physics Laboratory)
• 20:00
3.4 A steady state magnetic sensor for ITER and beyond: development and final design 30m

The measurement of the magnetic field in tokamaks such as ITER and DEMO will be challenging due to the long pulse duration, high neutron flux and elevated temperatures. The long duration of the pulse makes standard techniques, such as inductive coils, prone to large error. At the same time, the hostile environment, with repairs possible only on blanket exchange, if at all, requires a robust magnetic sensor. This contribution presents the final design of novel, steady-state, magnetic sensors for ITER. A poloidal array of 60 sensors mounted on the vacuum vessel outer shell contributes to the measurement of the plasma current, plasma-wall clearance, and local perturbations of the magnetic field. Each sensor hosts a pair of bismuth Hall probes, themselves an outcome of extensive R&D, including neutron irradiations (to 1023 n/m2), temperature cycling tests (73 – 473 K) and tests at high magnetic field (to 12 T). A significant effort has been devoted to optimize the sensor housing by design and prototyping. The production version features an indium-filled cell for in-situ recalibration of the onboard thermocouple, vital for the interpretation of the Hall sensor measurement. The contribution will review the potential use of similar Hall sensors in DEMO and the associated R&D program.

Speaker: Martin Kocan (ITER Organization)
• 20:30 22:31
Session #4, Monday Night Poster Session
• 20:30
4.1 A multiplexer-based Q-band multi-channel microwave Doppler backscattering reflectometer on the HL-2A tokamak 2h

Doppler backward scattering (DBS) reflectometer has proven to be a powerful technique to study the physics of L-H transition, plasma transport, GAM, and zonal flows though measurements of the perpendicular velocity of density fluctuations, and the radial electric field in plasmas. In this work, a Q-band 8-channel DBS reflectometer system based upon a low insertion loss multiplexer-based feedback loop microwave source, and quadrature demodulation have been designed, tested in the laboratory, installed and operated on the HL-2A tokamak. The SSB phase noise of the multiplexer -based feedback loop microwave source has a better SSB phase noise especially at high offset frequency (f > 100 kHz), compared with that of a typical commercial synthesizer. The 8 working frequency components of the new DBS reflectometer systems are 34 - 48 GHz with a frequency interval of 2 GHz, and the power variation of all frequency components is < 4 dB. They are developed to measure the localized intermediate wavenumber (k⊥ρ ~ 1–2, k⊥ ~ 2–10 cm−1) density fluctuations and the poloidal rotation velocity profile of turbulence. Details of the system design, laboratory tests, ray tracing estimation, and initial plasma results illustrate the capabilities of the multiplexer-based DBS reflectometers.

Speaker: Zhongbing Shi (Southwestern Institute of Physics)
• 20:30
4.2 Studies of impurity generation and transport by the line ratio method in TJ-II 2h

The fate of impurities launched into the plasma through plasma-wall interaction processes is determined by several basic characteristics of the plasma edge as well as by the nature of the underlying erosion mechanism, such as sputtering or evaporation. Upon a first ionization by electron collisions at the edge, the impurity starts to feel a variety of forces which ultimately determines its transport either to the core (pollution) or back to the wall (screening). Furthermore, the lifetime of plasma-facing materials is critically determined by local redeposition processed taking place near the LFS. In this work, liquid metal samples (Li, LiSn, and Sn) were exposed to TJ-II plasmas in a porous structure (CPS). The analysis of the spectroscopic signatures of Li and Sn, as well as that of their first ions in the visible range, was performed with spatial resolution in radial and toroidal directions by using a set of 16-channel PMs looking at the localized impurity source. From the analysis, the kinetic energy of the ejected neutral species, as well as the thermalization and transport of the resulting ions, is inferred. By using a high recycling impurity as He, injected as an atomic beam, values of the ion temperature profile at the edge are also deduced.

Speaker: Francisco Tabares (Fusion Laboratory)
• 20:30
4.3 Application of a novel soft X-ray camera based on 2-D Gas Electron Multiplier (GEM) detector for the EAST high neutron background plasmas 2h

A novel soft X-ray diagnosis has been designed for the Experimental Advanced Superconducting Tokamak (EAST) high neutron and/or gamma background discharges, which is based on a triple Gas Electron Multiplier with 2D imaging. With the working gas of mixed Ar (70%) and CO2 (30%), the GEM is sensitive to the X-ray photon energy below 30keV. This system is installed in the horizontal window A with a tangential angle of nearly 12 degree to the toroidal field on EAST aiming to directly identify core instabilities and heavy impurity transports etc. The spatial resolution is controlled by stepping motor which moves the GEM in front of a collimating pinhole to realize the zooming in/out function of the camera. Due to the limitation of movable distance, the maximum spatial resolution is 3 cm. A 100 um thickness of beryllium foil is used to cut off the low energy photon (<3keV) which guarantees a rational X-ray flux for high performance plasmas. The GEM has been tested in ENEA (Frascati) Laboratory by several X-ray sources which shows the ability to remove the white noise by setting environmentally determined threshold voltages. For the incoming campaign, this camera is applied to image the soft X-ray radiations for EAST high-performance shots with strong neutral beam injection heating.

Speaker: liqun HU (Institute of Plasma Physics, Chinese Academy of Sciences (ASIPP) )
• 20:30
4.4 Measurements of Bulk-Fluid Motion in Direct-Drive Implosions 2h

A newly developed neutron time-of-flight diagnostic with an ultrafast instrument response function has been fielded on the OMEGA laser in a highly collimated line of sight. By using a small plastic scintillator volume, the detector provides a narrow instrument response of ~2 ns FWHM while maintaining a large signal-to-noise ratio for neutron yields between 1010 to 1014. The OMEGA Hardware Timing System is used along with an optical fiducial to provide an absolute neutron time-of-flight measurement. The fast instrument response enables the accurate measurement of primary DT neutron peak shape while the optical fiducial allows for an absolute neutron energy measurement. Evidence of bulk-fluid motion in cryogenic targets is presented with measurements of the neutron energy spectrum. An extension of this method to four lines of sight is discussed, which would enable the measurement of the hot-spot center-of-mass velocity. This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0001944.

Speakers: Owen Mannion (Laboratory for Laser Energetics, University of Rochester), Vladimir Glebov (Laboratory for Laser Energetics, University of Rochester)
• 20:30
4.5 Plasma Current Profile Measurement by using improved Faraday rotation measurement of POlarimeter-INTerferometer for Long-Pulse Operation on EAST 2h

A double-pass, radially-view, 11 chord, POlarimeter-INTerferometer (POINT) system has been developed and routinely operated on the EAST tokamak, and provides important plasma current profile information for plasma control and physics understanding. Stray light originating from spurious reflections along the optical path and also direct feedback from the retro-reflector used to realize the double-pass configuration can both contribute to contamination of Faraday rotation measurement accuracy. Modulation of Faraday rotation signal due to interference from multiple reflections is observable when the interferometer phase (plasma density) varies with time. Direct reflection from the detector itself can be suppressed by employing an optical isolator consisting of λ/4-waveplate, and polarizer positioned in front of the mixer. A Faraday-effect phase oscillation observed during the density ramp can be reduced from 5o ~10o to 1o~2o by eliminating reflections from detector. Based on internal Faraday rotation measurement using this improved POINT system, the equilibrium reconstruction with a more accurate core current profile constraint has been demonstrated successfully for long-pulse operation high-performance scenario research on EAST.

Speakers: Haiqing LIU (Institute of Plasma Physics, Chinese Academy of Sciences (ASIPP) ), zhiyong zou ( Institute of Plasma Physics, Chinese Academy of Sciences)
• 20:30
4.6 Turbulence level effects on conventional reflectometry measurements observed in 2D full-wave simulations 2h

Numerical simulations are critical in improving the capabilities of microwave diagnostics. In this work, the 2D finite-difference time-domain full-wave code REFMUL [1] has been applied on broadband turbulent plasmas using the conventional reflectometry set-up.Simulations were performed with O-mode waves, fixed frequency probing and I/Q detection. Determining O-mode propagation, the plasma density ne was modeled as the sum of a mean component of constant radial gradient and a fluctuating component following the Kolgomorov-like amplitude k-spectrum. Constant plasma velocity, in either radial or poloidal direction, and two different ne gradients were considered. In each case, the turbulence level δne /ne was scanned over several orders of magnitude.Simulations show trends, such as spectral broadening of the complex A(t)eiφ(t) signals with increasing δne/ne, that are discussed taking into account geometrical and scattering efficiency competing effects. Variations in A(t) and φ(t) proportional to δne/ne are also shown, for low δne/ne as previously observed with other 1D and 2D codes. The onset of non-linear effects and association with phase jumps and runaway as well as Doppler effects, is also observed and discussed. [1] F. da Silva et al, J. Comput. Phys., 203 (2005), 467-492

Speakers: José Vicente (Instituto de Plasmas e Fusão Nuclear, Instituto Superior Técnico, Universidade de Lisboa), Filipe da Silva (Instituto de Plasmas e Fusão Nuclear, Instituto Superior Técnico, Universidade de Lisboa), Tiago Ribeiro (Max-Planck-Institut für Plasmaphysik), Stéphane Heuraux (Institut Jean Lamour, UMR 7198 CNRS - Université de Lorraine), Carlos Silva (Instituto de Plasmas e Fusão Nuclear, Instituto Superior Técnico, Universidade de Lisboa), Garrard Conway (Max-Planck-Institut für Plasmaphysik)
• 20:30
4.7 Electron temperature turbulence measurements on the high magnetic field side of the DIII-D tokamak 2h

Turbulence measurements in tokamaks have for the most part concentrated on the low field side (LFS) of the magnetic axis due to accessibility of measurements and conventional belief that high field side (HFS) turbulence is negligible compared to the LFS. This has led to HFS turbulence not been considered for turbulence model validation studies although it can be a stringent constraint. To address this issue, we have modified the UCLA eight-channel Correlation Electron Cyclotron Emission (CECE) system at DIII-D to locally probe both the LFS and HFS. CECE uses a cross-correlation technique to remove intrinsic thermal noise and reveal electron temperature turbulence. Typically, 2nd harmonic X-mode electron cyclotron resonance has been utilized on DIII-D when probing the LFS. In order to study turbulence on the HFS, fundamental O-mode emission is employed. The optical system was modified to minimize differences in spot sizes on LFS and HFS (e.g., wavenumber range). Laboratory tests have shown that the optical systems for HFS and LFS are comparable. Details on hardware modifications together with investigation of potential measurement issues will be described. Preliminary plasma data will also be presented. Supported by the U.S. DOE under DE-FG02-08ER54984 and DE-FC02-04ER54698.

Speaker: Choongki Sung (the department of physics and astronomy, UCLA)
• 20:30
4.8 Considerations of the q-profile control in KSTAR for advanced tokamak operation scenarios 2h

The q-profile control is essential for tokamaks exploring the advanced tokamak scenarios, which expected to be able to provide a possible route towards a steady-state high performance operation in a fully non-inductive current drive state. This is because the pressure and current profiles must remain optimal for the scenario during the injection of large amounts of heating and current drive. Here, essential tools for the q-profile control are the motional Stark effect (MSE) diagnostic for measuring the radial magnetic pitch angle profile and a state-of-the-art plasma control system. The pulse duration of the H-mode discharge at KSTAR has been extended year by year with improved control performance, and the experiment of ITB formation in a weakly reversed q-profile with a marginal NBI majority heating successfully demonstrated. These recent achievements are attributed to reliable profile measurement, which means that profile feedback control has become a necessary step to ensure a robust and reliable approach to advanced scenarios as the next step of research in KSTAR. In this work, we present the technical and conceptual requirements for the q-profile control according to the upgrade plan of heating and current drive systems in the coming years.

Speakers: Jinil Chung (National Fusion Research Institute), J. Ko (National Fusion Research Institute), S. -H. Hahn (National Fusion Research Institute), H. S. Kim (National Fusion Research Institute), S. J. Wang (National Fusion Research Institute)
• 20:30
4.9 Simulations of Scattered neutrons for the time of flight enhanced diagnostics (TOFED) neutron spectrometer at EAST 2h

The TOFED (double-ring Time-Of-Flight Enhanced Diagnostics) neutron spectrometer has been installed outside the EAST tokamak hall. The TOFED line of sight (LOS) is defined by the collimator through the wall of EAST hall, which can reduce scattered neutrons and background gamma-rays for the neutron spectral measurements. The Monte Carlo code MCNP5 is used in the simulations to characterize the collimation effect. The MCNP5 simulations show that background radiations at detectors have been reduced significantly which satisfies the requirement for TOFED operations at EAST. The angular distribution of the incident neutrons and the proportion of the scattered neutrons in the LOS of the TOFED are obtained for the measured spectral data interpretation.

Speaker: JIAQI SUN (Peking University)
• 20:30
4.10 FPGA - based Active - Feedback Laser Alignment System for the ITER Toroidal Interferometer and Polarimeter (TIP) 2h

The ITER TIP system design utilizes active feedback alignment to maintain laser position along the 120m long beam path from an optical table to the tokamak and back. This is accomplished using a series of high-speed piezoelectric tip-tilt mirror mounts, beam position sensing detectors (PSDs), and a custom feedback controller. The controller features a high-density Field Programmable Gate Array (FPGA) and utilizes digital signal processing (DSP) techniques to implement a variety of control algorithms including a high-speed proportional-integral-derivative (PID) loop. The versatility of the design allows the continued development of more refined and advanced control algorithms such as machine-learning and fuzzy-logic. A working system has been constructed using ITER-approved FPGA hardware components and installed on the DIII-D prototype TIP system. Results indicate that active alignment is important for meeting ITER requirements because of the large motions of the machine during operations and the need to stabilize the signals on the detectors during discharges. In addition, the design also provides a fail-safe feature for automatic re-alignment in case of temporary beam loss. *Work supported by U.S. DOE Contracts DE-AC-02-09CH11466 and DE-FC02-04ER54698

Speakers: Daniel Finkenthal (Palomar Scientific Instruments), R.A. Colio (Palomar Scientific Instruments), M.A. Van Zeeland (General Atomics), T.N. Carlstrom (General Atomics), A. Gatusso (General Atomics), R. O'Neill (General Atomics), R.L. Boivin (General Atomics), D. Johnson (Princeton Plasma Physics Laboratory, )
• 20:31
4.11 Neutron and gamma imaging aperture design for the National Ignition Facility 2h

The first neutron imaging system has proven to be a valuable tool for understanding the hot spot and cold fuel regions of imploding capsules. Changing the timing of the recording system allowed us to prove that we can use a similar setup to collect gamma images of the capsules. The design of the third line of sight pinhole incorporates the needs of both of these image types. This poster/paper will describe the design criteria and solution for this complex aperture array. LA-UR-18-20205

Speakers: Valerie Fatherley (Los Alamos National Laboratory), David Fittinghoff (LLNL), Justin Jorgenson (LANL), Petr Volegov (LANL), Carl Wilde (LANL)
• 20:31
4.12 Passive Detection of High Energy Particle Loss using Rippled Tiles 2h

A novel detection approach for energetic particle loss has been developed and implemented on DIII-D. Incident energetic ion flux has been observed to produce a measurable temperature change on the DIII-D outer wall during neutral beam injection. A challenge with detecting energetic particle losses is to distinguish their heat signature from SOL heat flux profiles. The new detection technique relies on modified tile geometries composed of short barricades to prevent small gyroradius particles from impacting the downstream wall surface. The regions deprived of energetic particle impacts should exhibit specific heat patterns that can be identified using IR imaging. The geometry of the tiles set the energetic particle energy and pitch angle sensitivity, both of which can be modeled to inform the tile design. Four rippled tiles are in use on DIII-D, with two near the midplane and two approximately 45o below the midplane. Simulations of prompt loss from counter-current neutral beam injection indicates unique heat patterns for each tile. Heating patterns are measured using a wide-angle, high-speed IR camera and the resulting images indicate that ripple tile shapes affect downstream ion impacts. This passive detection technique is potentially applicable to ITER-class fusion devices.

Speakers: Bruno Coriton (General Atomics), David Pace (General Atomics), Michael Van Zeeland (General Atomics), Charlie Lasnier (Lawrence Livermore National Laboratory), Christopher Murphy (General Atomics), Rejean Boivin (General Atomics)
• 20:31
4.13 Developing a long duration Zn K-alpha source for x-ray scattering experiments 2h

We are developing a long-duration K-alpha x-ray source at the OMEGA laser facility. Such sources are important for x-ray scattering measurements at small scattering angles, where high spectral resolution is required. To date, He-alpha x-ray sources are the most common probes in scattering experiments, using ns-class lasers to heat foils to keV temperatures resulting in K-shell emission from He-like charge states. The high temperature of the emitting plasma introduces significant thermal broadening, reducing the resolution of scattering measurements. Here, we combine the long duration of He-alpha sources with the narrow spectral bandwidth of cold K-alpha emission. Using a foil-stack target, we produced a Zn K-alpha source using a 1 ns laser pulse from the OMEGA laser. A Ge foil was irradiated by the OMEGA laser, producing Ge He-alpha emission, which pumped Zn K-alpha emission from a nearby Zn layer. Using this technique, we present a long duration K-alpha source suitable for scattering measurements. This work was supported by the US DOE under grant No. DE-NA0001859, under the auspices of the US DOE by Lawrence Livermore National Laboratory under Contract No. DE-AC52-07NA27344, and supported by Laboratory Directed Research and Development (LDRD) Grant No. 18-ERD-033.

Speakers: Michael MacDonald (University of California, Berkeley), Alison Saunders (University of California, Berkeley), Roger Falcone (University of California, Berkeley), Wolfgang Theobald (University of Rochester), Tilo Doeppner (Lawrence Livermore National Laboratory)
• 20:31
4.14 Fringe jump compensation techniques for the time-averaging zero-crossing phase measurement in the KSTAR millimeter-wave interferometer 2h

A new fringe jump compensation technique has been developed for a zero-crossing phase measurement that provides the phase detection within a single fringe. The algorithm is extremely useful in the case of the time-averaging zero-crossing technique on noisy environments. When the noise level over the measurements is not sufficiently suppressed, a backward slope appears near the fringe jump on the measured phase signal and this slope brings an ambiguity over the compensation process. The algorithm requires a simple circuit that provides additional channel to measure a half fringe shifted phase along with the original channel. At least one of these two channels will be placed at the outside of the backward slope on the fringe jump. Comparing the phases from two channels, the algorithm decides a more reliable channel. This system applied to the millimeter-wave interferometer on Korea Superconducting Tokamak Advanced Research (KSTAR) device, and successfully removed the ambiguity in the cases with severely deteriorated signals. The algorithm can provide a robust and cost-effective solution for the phase measurement system in many fields.

Speaker: Yong Un Nam (National Fusion Research Institute)
• 20:31
4.15 Measurement of the toroidal radiation asymmetry during massive gas injection triggered disruptions on J-TEXT 2h

Disruptions have the potential to cause severe damage to large tokamaks like ITER. The mitigation of disruption damage is one of the essential issues for tokamak plasmas. Massive gas injection (MGI) is a technique in which large amounts of noble gas is injected into the plasma in order to safely radiate the plasma energy evenly over the entire plasma-facing first wall. However, the radiated energy during the disruption triggered by massive gas injection is found to be toroidal asymmetric. In order to investigate the spatial and temporal structure of the radiation asymmetric, the radiated power diagnostics for the J-TEXT tokamak have been upgraded. A multi-channel array of ultraviolet photodiodes (AXUV) has been upgraded at four different toroidal positions to investigate the radiation asymmetries during massive gas injection. It is found that the toroidal asymmetry is associated with gas properties and MGI induced MHD activities

Speakers: Ruihai Tong (Huazhong University of Science and Technology), Zhongyong Chen (Huazhong University of Science and Technology), Xiaolong Zhang (Shenzhen University), Zhifeng Cheng (Huazhong University of Science and Technology), Wei Li (Huazhong University of Science and Technology), Wei Yan (Huazhong University of Science and Technology), Yunong Wei (Huazhong University of Science and Technology), Zhoujun Yang (Huazhong University of Science and Technology)
• 20:31
4.16 Novel quasi-optical front end for optimized cross-polarization scattering for magnetic turbulence measurements on the DIII-D tokamak# 2h

UCLA is continuing to develop a new generation diagnostic that utilizes cross-polarization scattering(1) (CPS) to measure the fluctuating internal magnetic fields in tokamaks. The CPS technique relies on magnetic turbulence to scatter EM radiation into the perpendicular polarization, enabling a local measurement of the magnetic fluctuations. This is a challenging measurement that addresses the contribution of magnetic turbulence to anomalous thermal transport in fusion relevant plasmas. The goal of the new quasi-optical design is to achieve the full spatial and wavenumber capabilities of the CPS diagnostic. The approach consists of independently controlled aiming systems for the probe and scattered EM beams (55-75 GHz). This is accomplished by internal focusing lenses and remotely controlled mirrors. This new quasi-optical front end was designed with the assistance of 3D plasma ray tracing and Gaussian beam propagation codes. The design of the lenses, mirrors, remote control components, vacuum interface, and testing will be presented. #Supported by US DOE under DE-FG02-08ER54984 and DE-FC02-04ER54698. (1)T. Lehner, et al., Europhys. Lett., 8 759 (1989), Linda Vahala, et al., Phys. Fluids B 4, 619 (1992), X.L. Zou, et al., Phys. Rev. Lettrs, 75, 1090 (1995)

Speakers: Juan Francisco Rivero-Rodriguez (Department of Mechanical Engineering and Manufacturing, University of Seville), Manuel Garcia-Muñoz (Department of Atomic, Molecular and Nuclear Physics, University of Seville), Richard Martin (CCFE, Culham Science Centre), Joaquin Galdon-Quiroga (Department of Atomic, Molecular and Nuclear Physics, University of Seville), Juan Ayllon-Guerola (Department of Mechanical Engineering and Manufacturing, University of Seville), Rob Akers (CCFE, Culham Science Centre), James Buchanan (CCFE, Culham Science Centre), David Croft (CCFE, Culham Science Centre), Daniel Garcia-Vallejo (Department of Mechanical Engineering and Manufacturing, University of Seville), Javier Gonzalez-Martin (Department of Mechanical Engineering and Manufacturing, University of Seville), Dan Harvey (CCFE, Culham Science Centre), Ken McClements (CCFE, Culham Science Centre), Mauricio Rodriguez-Ramos (Department of Atomic, Molecular and Nuclear Physics, University of Seville), Lucia Sanchis-Sanchez (Department of Atomic, Molecular and Nuclear Physics, University of Seville)
• 20:31
4.17 Development of a 30 – 165 GHz density profile reflectometer and performance evaluation for ITER 2h

Laboratory evaluation of an integrated 40-m transmission line (TL) that approximates the LFSR system for ITER is underway. The TL includes corrugated waveguide, miter bends, calibration mirror, waveguide switch, stray-radiation protection system, Gaussian telescope (GT), vacuum windows, and containment membranes. FMCW signals are generated by V- and D-band transceiver modules. Transmission signals are multiplexed for combined propagation through the TL. Test metrics include antenna pattern scans to determine mode content, power loss measurements, and homodyne detection of FMCW signals. A method for reference phase calibration with a modified TL-integrated miter mirror is investigated. The calibration feature is extractable from the intermediate frequency (IF) spectrum with sufficient S/N without affecting the main signal. Microwave performance with the prototype GT is relatively insensitive to GT position. A S/N estimate of the measurement on ITER is predicted by incorporating laboratory test results with calculations of expected noise levels and signal losses caused by the plasma. Current projections suggest that, with some further optimization of the transceivers, the LFSR will meet the 5-mm resolution requirement for ITER. *Work supported by PPPL under subcontract S013252-A.

Speaker: Christopher Muscatello (General Atomics)
• 20:31
4.18 Neutron emission spectroscopy of D plasmas at JET with liquid scintillating neutron spectrometer 2h

Neutron emission spectroscopy is a diagnostic technique that allows for energy measurements of neutrons born from nuclear reactions. The JET (Culham, UK) has a special place role in this respect as advanced spectrometers for 2.5 MeV and 14 MeV neutrons have been here developed for the first time for measurements of the neutron emission spectrum from D and DT plasmas with unprecedented accuracy. Twin liquid scintillating neutron spectrometers were built and calibrated at PTB (Braunschweig, Germany) and installed on JET in the recent years with tangential-equatorial (KM12) and vertical-radial (KM13) view lines, with the latter only recently operational. This article reports on the performance of KM12 and on the development of the data analysis methods in order to extract physics information upon D ions kinematics in JET auxiliary heated D plasmas from 2.5 MeV neutron measurements. The comparison of these results with the correspondents from other JET neutron spectrometers is also presented: Their agreement allows for JET unique capability of multi-lines of sight neutron spectroscopy and for benchmarking other 14 MeV neutron spectrometers installed on the same lines of sight in preparation for the DT experimental campaign at JET.

Speakers: Luca Giacomelli (IFP-CNR), Francesco Belli (EURATOM-ENEA sulla Fusione), Federico Binda (Department of Physics and Astronomy Uppsala University), Sean Conroy (Department of Physics and Astronomy Uppsala University), Jacob Eriksson (Department of Physics and Astronomy Uppsala University), Alberto Milocco (Dipartimento di Fisica “G. Occhialini”, Università degli Studi di Milano-Bicocca), Sergei Popovicev (CCFE Culham Science Centre), Brian Syme (CCFE Culham Science Centre)
• 20:31
4.19 Study of the properties of thin Li films and their relationship with He and H plasmas using Ion Beam Analysis in the DIONISOS Experiment 2h

Plasma facing component (PFC) conditioning dramatically affects plasma performance in magnetic confinement fusion experiments. Lithium (Li) has been used in multiple machines to condition PFC with subsequent improvements to plasma performance. Multiple studies have investigated the interactions of Li with deuterium (D) and oxygen (O) in order to ascertain the mechanisms behind improvements in performance. Ion Beam Analysis (IBA) is a useful tool to interrogate PFC surfaces as they interact with plasmas. DIONISOS is a linear plasma device, capable of generating discharges with fluxes~10^21m^-2s^-1 and Te~6 eV, coupled to an ion accelerator. DIONISOS is capable of analyzing samples using Elastic Recoils Detection (ERD) and Rutherford Backscattering Spectroscopy (RBS) during plasma exposures. The facility has been equipped with a Li deposition system for evaporation of thin coatings on different substrates. The evaporator enables real time ERD and RBS measurements of deposition and erosion of Li coatings on different substrates and the interaction of the Li with the vacuum and plasma. Considerations for ERD and RBS, e.g. ion species, energy, and data acquisition frequency, are presented. This work is the basis for further investigation of He, H and D retention in solid and liquid Li

Speakers: Felipe Bedoya (PSFC - MIT), Kevin Woller (PSFC - MIT), Dennis Whyte (PSFC - MIT)
• 20:31
4.20 Improvement of Infrared Imaging Video Bolometer for Application to LHD Deuterium Experiment 2h

InfraRed imaging Video Bolometer (IRVB) was improved for the application to the measurement under neutron environment of the deuterium experiment in the Large Helical Device (LHD). Plasma radiation measurement is crucial to understand the power balance and plasma detachment. Multi-dimensional measurement is required since the radiation occurs outside the last closed flux surface. IRVB is useful for the measurement and consists of a pinhole camera part with a Pt foil detector and an IR camera part. Deuterium plasma experiment was started from 2017 in LHD. (1) A shielding for the IR camera and (2) high-reproducibility and high-uniformity carbon coating on the Pt detector with the size of 130 mm x 100 mm x 2.5 micron for in-situ calibration of the thermal characteristics were required for the application of the IRVB under the neutron environment. Then, the neutron shielding was designed using MCNP6 code with the three-dimensional modeling of LHD. Evaporation technique was introduced to the carbon coating and the improved coating with 160-micron thickness could be obtained. Owing to these improvements, the IRVB was successfully operated in the neutron emission rate up to 3.3 × 10^15 n s^-1, which is the maximum rate in the first experimental campaign.

Speakers: Kiyofumi Mukai (NIFS), Ryota Abe (Sendai National College of Technology), Byron Peterson (NIFS), Sadatsugu Takayama (NIFS)
• 20:31
4.21 Investigating the Relationship between Noise Transfer inside the Gated X-ray Detectors Used on the National Ignition Facility and their Imaging Ability 2h

X-ray imaging at the National Ignition Facility (NIF) is performed by means of diagnostics that combine an imaging system (pinhole apertures or mirror-based x-ray microscopes) and a detector. A multitude of x-ray detectors are used on NIF, depending on the experimental requirements and constraints. All of these detectors have in common the fact that the x-rays are indirectly recorded: quanta are successively converted, amplified, or scattered; these three basic stages can take place in different orders and be repeated a different number of times. To predict how noise is transferred throughout these stages, we apply a cascaded linear model analysis to a Micro Channel Plate (MCP)-based framing camera. We establish a theoretical expression of the Noise Power Spectrum (NPS) at the detector’s output and assess its accuracy by comparing it to the NPS of Monte Carlo simulations of the detector’s response to a uniform illumination. We also demonstrate that fitting the NPS of experimental data against a parametric model based on this expression can yield valuable information on the Modulation Transfer Function (MTF) of framing cameras, for both DC-biased and pulsed MCP operation. Prepared by LLNL under Contract DE-AC52-07NA27344.

Speakers: Clement Trosseille (Lawrence Livermore National Laboratory), Laura Robin Benedetti (Lawrence Livermore National Laboratory), Mai Beach (Lawrence Livermore National Laboratory), Dustin Boyle (Lawrence Livermore National Laboratory), Dana Hargrove (Lawrence Livermore National Laboratory), Joe Holder (Lawrence Livermore National Laboratory), Alex Lumbard (Lawrence Livermore National Laboratory), Guy Ruchonnet (Lawrence Livermore National Laboratory), David Bradley (Lawrence Livermore National Laboratory)
• 20:31
4.22 Development of A Langmuir Probe Array for Mode Conversion Research 2h

To evaluate and monitor the edge electron density distribution, which decides the location and efficiency of X-B or O-X-B mode conversion, a Langmuir probe array with high spatial and temporal resolution is developed for Sino-UNIted Spherical Tokamak (SUNIST). The probe array consists of 37 single molybdenum probes, constituting 12 triple probes at a step of 4mm. In consideration of characteristic frequency of magnetohydrodynamics (MHD) behaviors (<20kHz) and main turbulent perturbations (~50kHz) for SUNIST, the bandwidth of the probe array is set to 60kHz, capable of evaluating influences of these instabilities on mode conversion process. Experimental results have proven that the Langmuir probe array can give a clear boundary density distribution with high temporal resolution.

Speakers: Shouzhi Wang (Tsinghua University), Zhe Gao (Tsinghua University), Yi Tan (Tsinghua University)
• 20:31
4.23 The First Operation of a Tangential Two-Color Interferometer in KSTAR 2h

A two-color interferometer (TCI) has been developed for the Korean Superconducting Tokamak Advanced Research (KSTAR) machine. The TCI is demonstrated first with a single tangential chord that traverses the innermost of the five chord planned. The long and short wavelengths for vibration compensation are 10.6 μm and 632.8 nm, respectively. Each wavelength beam is provided by commercial CO2 and He-Ne lasers. Under the KSTAR tokamak floor, a main optical table was installed for two lasers, a beam merging / splitting optics and detectors. Electronic devices and signal processing circuits are placed next to the optical table to lower the intermediate frequency (IF) to 10 MHz and detect the phase. The original IF is 40 and 80 MHz for CO2 and He-Ne lasers, respectively. The down-converted signal is injected into a quadrature demodulator to obtain the final phase signal. The effective vibration level is so large, causing multi-fringe data process like any other conventional interferometer, such as far-infrared or microwave. Therefore, fringe calculation errors may still occur. However, since the pure response of the phase to the plasma density is small in principle, it has been confirmed that even the newly installed pellet injector does not cause any fringe error in the TCI.

Speakers: June-Woo Juhn (National Fusion Research Institute), K. C. Lee (National Fusion Research Institute), H. M. Wi (National Fusion Research Institute), Y. S. Kim (National Fusion Research Institute), Y. U. Nam (National Fusion Research Institute)
• 20:31
4.24 Design of Ultra-fast Charge eXchange Recombination Spectroscopy diagnostic and photon flux simulation on EAST tokamak 2h

Four-channel Ultra-fast Charge eXchange Recombination Spectroscopy (UF-CXRS) diagnostic has been designed and is under construction on EAST tokamak. The key components of coating fiber bundles, spectrometer, lenses, detectors and data acquisition system are presented. The transmission of the whole optical path is designed to be about 50%. The temporal resolution of this diagnostic is 1 microsecond and the spatial resolution is at the order of centimeter. The photon flux of every channel is simulated by consulting ADAS data base basing on electron temperature and density profiles measured by Thomson Scattering and carbon ion C6+ simulated by Strahl code. The simulation result is compared with the experimental profile diagnosed by the traditional Charge eXchange Recombination Spectroscopy. It is shown that UF-CXRS channel will has a strong photon flux around the radial position of ρ=0.75, which is determined by C6+ profile peak. A 128-channel UF-CXRS system will be constructed in the nearly future.

Speaker: Minyou Ye (University of Science and Technology of China)
• 20:31
4.25 Development of optical probe for local emission profile measurements in Versatile Experiment Spherical Torus 2h

Optical probe has advantage of direct measurement although it may lead to plasma perturbation in contrast with conventional optical emission spectroscopy. An optical probe with outer diameter of 8 mm and viewing dump of knife-edge type is designed and installed in Versatile Experiment Spherical Torus (VEST) to measure local emissivity directly, which gives radial profiles of impurity emission intensities via shot-to-shot measurements at various radial positions. In the optical probe system, collimated light is transmitted via vacuum feed-through and collected to two types of spectroscopic system, i.e. spectrometer with electron multiplying charge coupled device (EMCCD) and band-pass filter with photo multiplier tube (PMT); the spectrum at specific time and time evolution of intensity in fixed wavelength can be obtained, respectively. Time evolution of radial electron density profile near the edge can be calculated by collisional-radiative model using ratio between Hα and Hβ line after intensity calibration. Besides, impurity emission profiles (e.g. oxygen, carbon) in several charge states of concern to impurity transport study can be measured. Then, Zeff will be also attainable using OPEN-ADAS database.

Speakers: Jae-young JANG (Department of Nuclear Engineering, Seoul National University), YooSung Kim (Department of Nuclear Engineering, Seoul National University), Kyoung-Jae Chung (Department of Nuclear Engineering, Seoul National University), Y. S. Hwang (Department of Nuclear Engineering, Seoul National University)
• 20:31
4.26 Plasma rotation measurement using UV/Visible spectroscopy on ADITYA-U tokamak 2h

A high-resolution spectroscopic diagnostic for the measurement of plasma rotation and ion temperature is designed, developed and implemented on ADITYA-U tokamak, which is built to have diverter configuration by Upgrading ADITYA tokamak [1]. The diagnostic is viewing the plasma along the toroidal direction through six lines of sights from midplane tangential port using optical fibers and collimating lenses and covering the plasma from center to the half radius of the plasma. The UV and visible emission lines are at 229.69, 227.09 and 529.01 nm from C2+, C4+, and C5+ have been selected for the measurement. A high-resolution 1m f/8.7 spectrometer equipped with 1800 g/mm is used along with a CCD for the measurement. Initial measurements to using the diagnostic have been carried out during the ADITYA-U operation. In this presentation, the details on the development of the diagnostics and initial result will be discussed [1] J Ghosh et al, proceeding FEC 2016

Speakers: Gaurav Shukla (Pandit Deen Dayal Petroleum University), Malay Chowdhuri (Institute for Plasma Research), Kajal Shah (Pandit Deen Dayal Petroleum University), Ranjana Manchanda (Institute for Plasma Research), K.B.K Mayya (Pandit Deen Dayal Petroleum University), Joydeep Ghosh (Institute for Plasma Research)
• 20:31
4.27 Conceptual design of the radial gamma ray spectrometers for ITER 2h

A set of gamma ray spectrometers have been designed for ITER under the Radial Gamma Ray Spectrometer (RGRS) project. Aim of this project is the design of a system integrated with the ITER Radial Neutron Camera able to measure the gamma rays emitted from the plasma with a good energy resolution (about 1.5% at 4.44 MeV) and at high rates (about 1 MHz). RGRS will be able to operate both in the D phase and in the full-power DT phase and will measure gamma rays from i) reactions between fast ions, such as a particles, and light impurities and ii) bremsstrahlung emission occurring when runaway electrons hit the tokamak edge or the bulk plasma. The RGRS detectors are arranged in 9 Lines of Sight (able to cover a radial region with r<a/3), each featuring a large LaBr3 scintillator crystal (3”x6”) coupled to a Photo Multiplier Tube. Due to high neutron flux and magnetic field several solutions have been adopted to guarantee a good Signal to Background ratio and counting capabilities. In this work the main RGRS features and performances will be illustrated. As it is designed, RGRS is capable to combine space and energy distribution measurements of a particle and runaway electrons, that will help, together with other diagnostics, the study of the fast ions physics in a burning plasma.

Speakers: Marica Rebai (IFP-CNR), Luciano Bertalot (ITER Organization), Benoit Brichard (F4E), Gabriele Croci (Università di Milano Bicocca), Basilio Esposito (ENEA), Ana Fernandes (Instituto de Plasmas e Fusao Nuclear), Luca Giacomelli (IFP-CNR), Giuseppe Gorini (Università di Milano BIcocca), Vitaly Krasilnikov (ITER Organization), Andrea Muraro (IFP-CNR), Rita Costa Pereira (Instituto de Plasmas e Fusao Nuclear), Enrico Perelli Cippo (IFP-CNR), Davide Rigamonti (IFP-CNR), Jacek Rzadkiewicz (National Center for Nuclear Research), Jorge Sousa (Instituto de Plasmas e Fusao Nuclear), Marco Tardocchi (IFP-CNR)
• 20:31
4.28 Wendelstein 7-X Bayesian Zeff inference in the Minerva framework 2h

Effective charge is an important physics parameter in magnetic confinement fusion research for understanding the behaviour of plasma impurities. A Bayesian model of Bremsstrahlung emission and the participating W7-X diagnostics has been developed in the Minerva framework. Since the Bremsstrahlung emission depends on electron density and temperature, the model includes Thomson scattering, interferometer, and spectroscopy diagnostics related to all relevant physics parameters. Gaussian processes have been used for tomographic inversion of the effective charge, electron density and temperature profiles. Profile hyperparameters are optimised by Bayes Occam’s razor criteria for optimal smoothness. The posterior distribution is explored by Markov chain Monte Carlo sampling, giving full uncertainties of all relevant physics quantities.

Speakers: Sehyun Kwak (Max-Planck-Institut für Plasmaphysik), Jakob Svensson (Max-Planck-Institut für Plasmaphysik), Andrea Pavone (Max-Planck-Institut für Plasmaphysik), Udo Höfel (Max-Planck-Institut für Plasmaphysik), Oliver Ford (Max-Planck-Institut für Plasmaphysik), Maciej Krychowiak (Max-Planck-Institut für Plasmaphysik), Lilla Vanó (Max-Planck-Institut für Plasmaphysik), Sergey Bozhenkov (Max-Planck-Institut für Plasmaphysik), Petra Kornejew (Max-Planck-Institut für Plasmaphysik), Young-chul Ghim (KAIST)
• 20:31
4.29 Comparative study of L1 & L2 type Phillip-Tikhonov regularization based tomographic reconstruction for simulated Heliotron–J Soft X-ray measurements 2h

Tomographic reconstructions of line integrated SX plasma measurements are an ill-conditioned problem, therefore, resorts to regularization. Regularization overcome ill-conditions and over-fitting issues by introduction of controlled penalty function (PF). L1 regularization PF considers absolute weights of parameters and shrinks less important weights to zero or very less. This results in a smooth but sparse image. L2 regularization PF involves squared weights of parameters and penalized large weights while retaining total number of parameters, which offers spars-less, very smooth image. L2 regularization exhibit invariant to rotation and scale, unique solution and efficient computation, whereas superior smoothness purges sharp transitions and trims edge futures visibility. Results from a comparative study of L1 & L2 Phillip-Tikhonov regularization based tomographic reconstructions of simulated Heliotron-J SX signals are presented. Line integrated SX data is estimated from flux surface information provided by VEMC code and contribution matrix for the viewing geometry is determined. Generalized cross validation method is employed for regularization parameter. Reconstruction is performed by minimization of least mean square error function under L1 & L2 penalty function.

Speakers: Shishir Purohit (SOKENDAI, The Graduate University for Advanced Studies), Yasuhiro Suzuki (SOKENDAI, The Graduate University for Advanced Studies , National Institute for Fusion Science), Satoshi Ohdachi (SOKENDAI, The Graduate University for Advanced Studies , National Institute for Fusion Science), Satoshi Yamamoto (Institute of Advanced Energy, Kyoto University)
• 20:31
4.30 Means of alignment observation and evaluation integrated into plasma diagnostics based on Thomson scattering 2h

In order to ensure proper operation of plasma diagnostics based on Thomson scattering (TS), precise adjustment and proper alignment of both the laser beam path and the collection optics of scattered light is of great importance to provide reliable and accurate measurements. Misalignment, permanent or intermittent, could result in incorrectly determined plasma (electron) density or even prevent the usability of this type of diagnostic at all. Therefore, suitable means of alignment monitoring should be integrated into each TS diagnostic system. One of the methods commonly used for alignment observation consists in an individual evaluation of signals obtained from a given fiber bundle split in halves. The ratio of corresponding intensities serves as a suitable tool. This work presents variations of the method based on this principle. Correlation of acquired intensity ratios with the performed measurements of vibrations of the TS collection optics structure on the COMPASS tokamak is discussed. Various techniques of optimization of alignment monitoring are shown. The optimal technique, which could be accommodated during construction of TS diagnostic systems on future fusion devices, is proposed.

Speakers: Miroslav Sos (Institute of Plasma Physics, Czech Academy of Sciences), Petr Bohm (Institute of Plasma Physics, Czech Academy of Sciences), Petra Bilkova (Institute of Plasma Physics, Czech Academy of Sciences), Matej Peterka (Institute of Plasma Physics, Czech Academy of Sciences), Ondrej Grover (Institute of Plasma Physics, Czech Academy of Sciences), Vladimir Weinzettl (Institute of Plasma Physics, Czech Academy of Sciences), Martin Hron (Institute of Plasma Physics, Czech Academy of Sciences), Radomir Panek (Institute of Plasma Physics, Czech Academy of Sciences)
• 20:31
4.31 Validation of fast-ion prompt loss measurements during neutral-beam heated plasmas on EAST* 2h

To investigate the fast-ions loss behaviour in high-performance plasmas on EAST, a scintillator-based fast-ion-loss detector (FILD) has been developed. The FILD has two measurement system, i.e. fast camera and photomultiplier tube (PMT) array. The fast camera can measure the pitch angle from 60◦ to 120◦ and the gyroradius from 10 mm to 180 mm of escaping fast ions reaching the detector, and the PMT detector is an array of 25 channels (5×5) and the sampling rate for PMT signal is 2 MHz per channel. In this paper, we will present the study of fast-ion prompt loss measurements with four different neutral beam (NB) lines together with prompt loss fast-ion orbit calculations. The transit time of the prompt loss orbit caused by the left co-injected NB is calculated to validate the diagnostic by comparing the simulation with the onset of fast-ion loss relative to the filtered fast ion D-alpha (f-FIDA) and the prompt loss distribution. By providing the pitch angles and gyro-radius of incident fast ions, we use the ion orbit loss model to calculate the trajectories of the incident ions backwardly in time to their birth at the intersection of the reverse orbit, and an overlaid NB injection footprint.

Speakers: C.R. Wu (Institute of Plasma Physics, Chinese Academy of Sciences), J. Huang (Institute of Plasma Physics, Chinese Academy of Sciences), J.F. Chang (Institute of Plasma Physics, Chinese Academy of Sciences), J. Zhang (Institute of Plasma Physics, Chinese Academy of Sciences), W. Gao (Institute of Plasma Physics, Chinese Academy of Sciences), Z. Xu (Institute of Plasma Physics, Chinese Academy of Sciences), M. Isobe (National Institute for Fusion Science, National Institutes of Natural Sciences), K. Ogawa (National Institute for Fusion Science, National Institutes of Natural Sciences)
• 20:31
4.32 A Novel Scintillator-based Neutron Imaging System for the National Ignition Facility 2h

The Los Alamos National Laboratory Advanced Imaging Team will soon deploy a novel neutron imaging system along a new line of sight at the National Ignition Facility (NIF). The new detector system will complement an existing equatorial active scintillator-based system and a passive image plate-based system along the polar direction. The third line of sight will allow true three-dimensional reconstruction of both the hot and cold fuel in the inertial confinement fusion process. Extensive scintillator characterization measurements of over 20 scintillator samples at the Los Alamos Neutron Science Center and the Omega laser facility in Rochester, NY, have informed key design decisions for the new detector. We conclude the feasibility of a monolithic lens-coupled design over the existing fiber array system. The monolithic design shows higher spatial resolution, higher light output, and better noise characteristics. A prototype of the novel system was recently tested at Omega and first penumbral images have been obtained with a neutron aperture array. Future work will include the lens design for the system, aiming for deployment at NIF in 2019.

Speakers: Verena Geppert-Kleinrath (Los Alamos National Laboratory), Matthew Freeman (Los Alamos National Laboratory), Frank Merrill (Los Alamos National Laboratory), Joshua Tybo (Los Alamos National Laboratory), Petr Volegov (Los Alamos National Laboratory), Carl Wilde (Los Alamos National Laboratory)
• 20:31
4.33 Bayesian uncertainty calculation in neural network inference of ion and electron temperature profiles at W7-X 2h

We show a method that combines Bayesian modelling and neural networks (NNs) to have a reliable and real time capable inversion scheme of X-ray imaging diagnostic data for the inference of ion and electron temperature profiles at Wendelstein 7-X. The feasibility of such an approach relies on the implementation of the diagnostic model within the Minerva Bayesian modelling framework: in this context a model is defined as the combination of the prior distributions over the free parameters, the physics relations describing the processes and the likelihood distribution on the observed quantities. Such implementation is used to create the neural network training set, sampling from properly chosen prior distributions. In this way the NN will learn a surrogate model of the model and its inverse. In order to provide a sensible NN inversion, the uncertainties of the NN model are calculated in a Bayesian fashion. The uncertainty of the NN prediction is calculated under the Laplace approximation of the posterior distribution of the learnt weights. The NN is then evaluated on real data and the prediction is compared to the standard Bayesian inference results. The analysis time with NN is reduced from a few hours to tens of microseconds allowing for real time application.

Speakers: Andrea Pavone (Max-Planck Institute for Plasma Physics), Jakob Svensson (1Max-Planck-Institute for Plasma Physics), Andreas Langenberg (1Max-Planck-Institute for Plasma Physics), Novimir Pablant (2Princenton Plasma Physics Lab), Udo Hoefel (1Max-Planck-Institute for Plasma Physics), Sehyun Kwak (1Max-Planck-Institute for Plasma Physics), Robert C. Wolf (1Max-Planck-Institute for Plasma Physics), Wendelstein 7-X Team (1Max-Planck-Institute for Plasma Physics)
• 20:31
4.34 DIII-D Faraday-Effect Polarimeter for Fast Magnetic Dynamics Measurement 2h

A Radial-Interferometer-Polarimeter (RIP) diagnostic has been developed to explore fast magnetic dynamics in high-performance DIII-D plasmas by measuring radial magnetic field perturbations using three chords positioned near the magnetic axis. Newly developed solid-state sources operated at 650 GHz are used and provide phase noise down to 0.01 degree/sqrt(kHz) and tunable bandwidth up to 10 MHz. Various systematic errors, which can contaminate the Faraday-effect polarimetric measurement, have been investigated in detail. The impact of the perpendicular magnetic field (Cotton-Mouton Effect) is evaluated and found negligible. Distortion of circular polarization due to non-ideal optical components is calibrated by using a rotating quarter wave-plate technique. Optical feedback, due to multiple reflections induced by the double-pass configuration, is reduced by increasing the damping of stray light. Error due to non-collinearity is minimized to less than 0.5 degree for electron density up to 1x1020m-3 by optimizing the alignment. Measurement of coherent and broadband high-frequency magnetic fluctuation for DIII-D H-mode plasmas is presented. This material is based upon work supported by the Department of Energy under Award Numbers DE-FG03-01ER54615 and DE-FC02-04ER54698.

Speakers: Jie Chen (Physics & Astronomy, UCLA ), Weixing Ding (Physics & Astronomy, UCLA ), David Brower (Physics & Astronomy, UCLA ), Daniel Finkenthal (Palomar Scientific Instruments), Rejean Boivin (General Atomics )
• 20:31
4.35 Simulation of the beamline thermal measurements to derive particle beam parameters in the ITER neutral beam test facility 2h

Injection of high energy neutral beam particles will be used in the ITER experiment for plasma heating and current drive. In a ITER heating beam injector, 40 MW electrostatically accelerated negative beam will be neutralised and filtered along the beamline obtaining a nominal 16.5 MW neutral beam power to be injected in the tokamak plasma or intercepted during conditioning and commissioning. The beam will heat the active panels of the beamline components with up to 13 MW/m2 surface power density and 18 MW power. These extreme conditions require testing in a ITER full scale neutral beam test facility under construction in Padova where the temperature of the beamline components will be monitored by 600 embedded thermocouples for protection against critical conditions, for recognising beam conditioning, and for deriving beam parameters. Power density maps of the expected beam-component interactions are applied on a non-linear finite element model of the entire beamline to simulate maps of surface temperatures. Such thermal maps are analysed to derive the beam parameters during operation: divergence of 3-7 mrad, misalignment of 2 mrad, and non-uniformity of 10%. The sensitivity of the temperature measurements is discussed considering a 10% fraction of the nominal beam power.

Speakers: Mauro Dalla Palma (CNR - Consorzio RFX), Emanuele Sartori (Università di Padova - Consorzio RFX), Matteo Zaupa (CNR - Consorzio RFX), Roberto Pasqualotto (CNR - Consorzio RFX)
• 20:31
4.36 Fast-framing camera based observations of spheromak-like plasmoid collision and merging process using two magnetized coaxial plasma guns 2h

We have been conducting compact toroid (CT) collision and merging experiments by using two magnetized coaxial plasma guns (MCPG) [1]. As is well known, an actual CT/plasmoid moves macroscopically in a confining magnetic field [2]. Therefore, three-dimensional measurements are important in understanding the behavior of the CTs. To observe the macroscopic process, we adopted a fast-framing camera developed by NAC Image Technology: ULTRA Cam HS-106E. The characteristics of this camera are as follows; a CCD color sensor, capable of capturing 120 images during one sequence with a frame rate of up to 1.25 MHz. Using this camera, we captured the global motion of a CT inside the magnetic field and the collision of two CTs at the mid-plane. Additionally, by using a color sensor, we captured the global change in plasma emission of visible light during the CT collision/merging process. As a result of these measurements, we determined the CT’s global motion and the changes in the CT’s shape and visible emission. The detailed system setup and experimental results will be presented and discussed. [1] I. Allfrey et al., Bull. Am. Phys. Soc. 62, BP11.00054 (2017). [2] T. Matsumoto et al., Rev. Sci. Instrum. 87, 11D406 (2016).

Speakers: Tadafumi Matsumoto (TAE Technologies, Inc.), Thomas Roche (TAE Technologies, Inc.), Ian Allfrey (TAE Technologies, Inc.), Hiroshi Gota (TAE Technologies, Inc.), Tomohiko Asai (Nihon University), Akiyoshi Hosozawa (Nihon University), Fumiyuki Tanaka (Nihon University), TAE Team (TAE Technologies, Inc.)
• 20:31
4.37 Two monochromatic channels high resolution X-ray imaging of laser produced plasma using Fresnel zone plate 2h

Monochromatic X-ray imaging at micron scale is a convenient tool for studying the dense plasma produced by laser facilities. We use a microscope made of a gold transmission Fresnel Phase Zone plate (FPZP) which has high spatial resolution capability (1-5 µm) and high efficiency so called Fresnel Ultra High Resolution Imager (FUHRI). We show the interest to combine a FPZP with a multilayer mirror (ML) which selects a narrow X-ray bandwidth. This device allows to choose the imaging wavelength by modifying the focal length and the angle of ML. Following the development of this diagnostic we have improved the system by using two side-by-side FPZPs, or bi-FPZP, in order to image two different photon energies range simultaneously. We present experimental imaging studies of plasma X-ray sources with FPZP’s at the following material edges with corresponding photon energies of: Ti Heα (~4.7 keV), Al Heβ (~1850 eV) and Al Lyβ (~2050 eV). \A second set of bi-FPZP, manufactured by the Paul Scherrer Institut (PSI)a, with smaller outermost zone width of 120 nm and a larger aperture, were designed to simultaneously observe Al Heβ and Lyβ lines. We compare the radiography measurement using such FZPs realized at EQUINOX laser facility (CEA). a)https://www.psi.ch/

Speakers: Alexandre Do (LULI), Michelle Briat (Commissariat à l’Energie Atomique ), Christophe Rubbelynck (Commissariat à l’Energie Atomique ), Maxime Lebugle (Paul Scherrer Institut), Christian David (Paul Scherrer Institut), Philippe Troussel (Commissariat à l’Energie Atomique )
• 20:31
4.38 Thomson Scattering measurements on DIII-D using in-vessel laser mirrors to diagnose a new divertor location 2h

Translatable in-vessel mirrors have enabled the DIII-D Thomson Scattering system to diagnose the divertor plasma in high triangularity plasma shapes. Previous divertor Thomson scattering measurements in DIII-D were restricted to spatial locations along a Nd:YAG laser beam that was directed through a vertical port. This only allowed measurements to be made in low triangularity shaped plasmas. The new mirrors re-route the laser underneath floor tiles to a position of smaller major radius as necessary for high triangularity plasmas. New in-vessel collection optics transmit scattered light from regions inaccessible to external lenses. Damage to mirrors and high stray light levels are challenges that were overcome to successfully make these measurements. Through the careful use of baffles and light shields, stray light leakage into polychromator detector channels was reduced to negligible levels, allowing temperature measurements below 1 eV. The system is described and initial results presented.

Speakers: T.N. Carlstrom (General Atomics), F. Glass (General Atomics), D. Du (General Atomics), A.G. McLean (A.G. LLNL), D Taussig (General Atomics), R. Boivin (General Atomics)
• 20:31
4.39 A diagnostic ion beam detector to measure poloidal magnetic flux 2h

Local, non-perturbative measurements of current density and magnetic fluctuations in magnetically confined fusion plasmas will provide information to advance equilibrium, transport, and stability studies. We are developing a diagnostic ion beam detector and technique (based on conservation of canonical momentum) to determine localized poloidal flux, flux fluctuations, poloidal magnetic field, and toroidal current density in axisymmetric toroidal plasmas from measurements of ion velocity. A K+ beam has been injected into reversed field pinch plasmas and the detector used to successfully measure the intensity and incoming angle of K2+ ions created along its path. We have developed simulation tools, including effects of field asymmetries, to unfold the poloidal flux from measurement of the beam angle and establish accuracy of the technique. Temporal and angular variations of measured signals are consistent with simulations. Since the detector operates with a direct view of the plasma, we have developed features to reduce noise currents induced by plasma particles and photons. The detector and technique also target a goal of developing more compact and economical diagnostic tools that retain heavy ion beam probe attributes. This work is supported by US DoE Award DE-SC0006077.

Speakers: P.J. Fimognari (Xantho Technologies, LLC), T.P. Crowley (Xantho Technologies, LLC), D.R. Demers (Xantho Technologies, LLC), T.D. Kile (Xantho Technologies, LLC)
• 20:31
4.40 Measuring across shock fronts using the Imaging Thomson Scattering diagnostic at OMEGA 2h

We report use of the spatially resolved imaging Thomson scattering diagnostic (ITS) to measure plasma properties across a shock on the OMEGA laser. Although the use of x-ray Thomson scattering to measure shock properties has been demonstrated, similar use in the optical regime has not been widely reported. The shocks are generated in a low-density, laser-driven, collisional carbon plasma impinging on a magnetized wire obstacle. Probing 42 degrees to the shock normal with a $2\omega$ beam, the ITS diagnostic successfully measured plasma parameters in and across the shock front. From the scattered spectra we observe electron number density jumps consistent with those of strong shocks. We compare how the probe beam affects the measurement for two pulse durations and energies, and discuss the issues that arise when probing a shock. This work is funded by the U.S. Department of Energy, through the NNSA-DS and SC-OFES Joint Program in High-Energy-Density Laboratory Plasmas, grant number DE-NA0002956, and the National Laser User Facility Program and William Marsh Rice University, grant number, R19071, and through the Laboratory for Laser Energetics, University of Rochester by the NNSA/OICF under Cooperative Agreement No. DE-NA0001944.

Speakers: Joseph Levesque (University of Michigan), Carolyn Kuranz (University of Michigan), Rachel Young (University of Michigan), Andy Liao (Rice University), Patrick Hartigan (Rice University), Mario Manuel (General Atomics), Sallee Klein (University of Michigan), Matthew Trantham (University of Michigan), Gennady Fiksel (University of Michigan), Joseph Katz (Laboratory for Laser Energetcis)
• 20:31
4.41 Using time-resolved penumbral imaging to measure low x-ray emission signals from capsule implosions at the NIF 2h

"We have developed an experimental platform at the National Ignition Facility to measure x-ray Thompson scattering (XRTS) spectra from indirectly-driven capsule implosions that create extreme density conditions near stagnation [1]. To account for shot-to-shot fluctuations in the implosion timing, we use x-ray self-emission at stagnation as a timing fiducial. Due to lower implosion velocity, low gas fill, and hot spot symmetry perturbations, the hot spot emission is 100 – 1000x weaker than that of standard ICF implosions. To address this challenge, we have developed and fielded a new pinhole-imaging snout that exploits time-resolved penumbral imaging [2,3]. Though use of 150 m diameter, penumbral-quality pinholes reduces the direct spatial resolution of the images, a 2D image can be reconstructed through analysis of the penumbra. Despite fluctuations of the x-ray flash intensity of up to 5x, the emission time history is strikingly similar from shot to shot, and slightly asymmetric with respect to peak x-ray emission. Emission times vary by up to 250 ps and can be determined with an accuracy of 50 ps. 1. D. Kraus et al, J. Phys.: Conf. Series 717, 012067 (2016). 2. B. Bachmann et al., Rev. Sci. Instrum. 85, 11D614 (2014). 3. B. Bachmann et al., Rev. Sci. Instrum. 87, 11E201 (2016)."

Speakers: David Bishel (Lawrence Livermore National Laboratory), Benjamin Bachmann (Lawrence Livermore National Laboratory), Austin Yi (Los Alamos National Laboratory), Dominik Kraus (Helmholtz-Zentrum Dresden-Rossendorf), Paul Neumayer (Gesellschaft für Schwerionenphysik), Alison Saunders (University of California, Berkeley), Michael MacDonald (University of California, Berkeley), Otto Landen (Lawrence Livermore National Laboratory), Laurent Divol (Lawrence Livermore National Laboratory), Tilo Doeppner (Lawrence Livermore National Laboratory)
• 20:31
4.42 A Four wavelength multi-spectral imaging system for Alcator C-Mod and TCV 2h

The Multi-Spectral Imaging system is a new diagnostic that captures simultaneous spectrally filtered images from a common line of sight while maintaining a large étendue. Imaging several atomic line intensities simultaneously may enable numerous measurement techniques. For example, Helium line ratios can produce 2D maps of Te and ne, and Balmer line intensities can be utilized to produce 2D maps of ne and volume recombination. The system uses a polychromator layout where each image is sequentially filtered and focused on to an industrial camera. The polychromator has 96% transmission between spectral channels with minimal vignetting and aberrations. A four-wavelength system was installed on C-Mod and then moved to TCV. The images are absolutely calibrated and spatially registered enabling 2D mappings of atomic line ratios and absolute line intensities. The CIII, and Balmer lines have been used to study detachment in the TCV divertor. The spectral transmissions were calibrated using an incandescent lamp with a known emissivity spectrum. The images are registered by cross-referencing points on TCV with a CAD model, and the images are inverted using the simultaneous algebraic reconstruction technique. This work was supported by USDoE awards DE-FC02-99ER54512 and DE-AC05-06OR23100

Speakers: Bryan Linehan (MIT PSFC), Robert T Mumgaard (MIT PSFC), Mirko Wensing (Ecole Polytechnique Fédérale de Lausanne), Basil P Duval (Ecole Polytechnique Fédérale de Lausanne), Kevin Verhaegh (York Plasma Institute, University of York), Christian Theiler (Ecole Polytechnique Fédérale de Lausanne), Yanis Andrebe (Ecole Polytechnique Fédérale de Lausanne), James Harrison (CCFE, Culham Science Centre)
• 20:31
4.43 Fielding the Pulse-Dilation Photomultiplier Tube onto the Gas Cherenkov Detector at NIF WellDIM3.9m 2h

The third generation Gas Cherenkov Detector has helped characterize gamma reaction history, but the output signal has been restricted to ~100ps by the temporal resolution of existing photomultiplier tube (PMT) technology. Replacing the existing photomultiplier tube with a newly fielded pulse-dilation photomultiplier tube (PD-PMT) has made it possible for the detector to further characterize implosion bang time and burn width given a refined resolution of ~10ps. The mechanical design of the Phase II Gas Cherenkov Detector has integrated these modern photomultiplier tube capabilities with the original detector to reveal gamma reaction history features that have not been available in the past. This poster/paper will highlight the design challenges, methodologies, and solutions developed to implement this new technology onto the existing detector at NIF. LA-UR-18-20252

Speaker: Benjamin Pederson (Los Alamos National Laboratory)
• 20:31
4.44 Extreme Ultraviolet Spectroscopy in the Divertor of DIII-D 2h

Extreme ultraviolet (EUV) spectroscopy has been added to the DIII-D divertor to measure dominant resonance-line radiators for low-Z elements, allowing determination of emissions and radiated power from constituent plasma species. This added spectroscopy enables detailed comparison and validation with 2D fluid boundary codes at conditions throughout the transition to divertor detachment. The spectrometer is a SPRED (Survey, Poor Resolution, Extended Domain) McPherson Model 251 with gratings to observe the 110-1700Å region with up to 2Å optical resolution. The broader grating provides views of C II-IV emission lines (especially C IV, 1550Å) as well as the D Lyman-α line, 1215Å, which together radiate >80% of the total power in the divertor. Divertor SPRED (or DivSPRED) is mounted on top of DIII-D with a direct vertical line of sight into the machine coincident with other boundary diagnostics. This position on the machine introduces challenges including radiation and magnetic sensitivity for vacuum pumps and detectors. The system and a discussion of engineering issues overcome are presented. *This work was supported in part under the auspices of the US Department of Energy (US DOE) by LLNL under DE-AC52-07N27344 and by the US DOE under DE-AC05-00OR22725, and DE-FC02-04ER54698.

Speakers: Adam McLean (LLNL), Steve Allen (LLNL), Rejean Boivin (General Atomics), Ron Ellis (LLNL), Ian Holmes (General Atomics), Ron Isler (ORNL), Aaro Jarvinen (LLNL), James Kulchar (General Atomics), Michael LeSher (General Atomics), Grant Marcy (General Atomics), Cameron Samuell (LLNL), Morgan Shafer (ORNL), Vlad Soukhanovskii (LLNL), Doug Taussig (General Atomics), Dan Thomas (General Atomics), Bob Williams (General Atomics)
• 20:31
4.45 High-resolution and high energy x-ray penumbral imaging of layered DT implosions on the NIF 2h

We present the status and progress of x-ray penumbral imaging of layered DT implosions on the NIF [1-3]. When imaging ICF hot spots with penumbral imaging, the increased aperture solid angle leads to up to a 100-fold increased photon flux in comparison to regular pinhole imaging. This increased flux and resulting improvement in SNR gives us experimental access to the hot spot self-emission spectrum that is beyond the ablator opacity threshold (~15 keV) and thus allows us to obtain unobstructed, high-resolution (5 micrometer) images of the hot spot. This is achieved by increased x-ray filtration which brings the emission weighted average x-ray energy from ~9 keV (pinhole imaging) to 17 - 30 keV. We will further describe the potential of x-ray penumbral imaging for enabling spatially resolved measurements of Te and mix in ICF DT implosions, which are key measurements for improving our understanding of the hot fuel assembly and evolution. References [1] B. Bachmann et al., Rev. Sci. Instrum. 85, 11D614 (2014) [2] B. Bachmann et al., Rev. Sci. Instrum. 87, 11E201 (2016) [3] B. Bachmann et al., Proc. SPIE 10390, 103900B (2017) This work performed under the auspices of the U.S. DOE by LLNL under Contract DE-AC52-07NA27344 and was supported in part by GA under Contract DE-NA0001808.

Speakers: Benjamin Bachmann (Lawrence Livermore National Lab), Hatim Abu-Shawareb (General Atomics), Neil Alexander (General Atomics), Jay Ayers (LLNL), Chris G. Bailey (LLNL), Perry Bell (LLNL), Laura R. Benedetti (LLNL), David Bradley (LLNL), Gilbert Collins (University of Rochester, LLE), Laurent Divol (LLNL), Tilo Doeppner (LLNL), Sean Felker (LLNL), John Field (LLNL), Andrew Forsman (General Atomics), Justin Galbraith (LLNL), Michael Hardy (LLNL), Terry Hilsabeck (General Atomics), Niko Izumi (LLNL), Charles Jarrott (LLNL), Joe Kilkenny (General Atomics), Steven Kramer (LLNL), Otto L. Landen (LLNL), Tammy Ma (LLNL), Andrew MacPhee (LLNL), Nathan Masters (LLNL), Sabrina Nagel (LLNL), Arthur Pak (LLNL), Prav Patel (LLNL), Louisa A. Pickworth (LLNL), Joseph E. Ralph (LLNL), Chris Reed (General Atomics), James R. Rygg (LLNL), Daniel B. Thorn (LLNL)
• 20:31
4.46 Superlinearity, Saturation, and the PMT—Tailoring and Calibration Methodology for Prompt Radiation Detectors 2h

Photomultiplier tubes, particularly those for high energy density physics, ideally operate over many orders of magnitude with linear response. We examine nonlinear response and mitigation strategies to extend the maximum linearity for metal mesh, plate, or glass MCP PMT. Superlinearity here means a positive nonlinear response and extension of linear operational limits by counteracting saturation mechanisms—charge depletion, space-charge field, and secondary emission surface effects. Our detector calibration methodology uses NIST-traceable calibrated standard laboratory equipment, and absolute input-referenced techniques to examine impulse or step responses separately as these are no longer related through linear integration. Quantitative analysis reveals nonlinearity strength independent of charge depletion. We further present a whole-detector radiation sensitivity calibration method using high-activity Co-60 sources, precise collimation, and NIST-calibrated flux measurement. Accurate characterization of nonlinear response and tailoring of the PMT circuitry can effectively produce higher linear current and charge limits. Recent results are also applicable to MCP PMT. This work was done by MSTS, LLC under Contract DE-NA0003624 with the U.S. Dept. of Energy. DOE/NV/03624—0027

Speakers: Robert Buckles (National Nuclear Security Site), Irene Garza (National Nuclear Security Site), Joseph Bellow (National Nuclear Security Site), Ken Moy (National Nuclear Security Site), Gordon Chandler (Sandia National Laboratory), Ruiz Carlos (Sandia National Laboratory), Brent Jones (Sandia National Laboratory)
• 20:31
4.47 Measurements of nonresonant inelastic X-ray scattering for the characterization of warm dense Argon plasmas at the Linac Coherent Light Source 2h

Bound-free contributions to X-ray Thomson scattering, or nonresonant inelastic X-ray scattering from core or semi-core electrons, is a powerful technique to probe matter in extreme conditions. Here we present measurements of high signal-to-noise, spectrally resolved X-ray scattering from cryogenic solid Argon, enabling future studies of ionization, densities, temperatures, and conductivity dynamics from ps-laser driven samples approaching material temperatures of 1 eV. Our results show energy resolved measurements of incoherent X-ray scattering with unprecedented dynamic range using a 120 Hz coherent X-ray laser coupled with a novel Argon micro-jet platform. Measurements were performed using a energy-dispersive spectrometer equipped with a Highly Annealed Pyrolytic Graphite (HAPG) crystal in combination with a Cornell-SLAC Pixel Array Detector (CSPAD) that was configured in the von Hamos geometry.

Speakers: Luke Fletcher (SLAC National Accelerator Laboratory), Siegfried Glenzer (SLAC National Accelerator Laboratory), Bastian Witte (SLAC National Accelerator Laboratory), Emma McBride (AC National Accelerator Laboratory), Thomas White (University of Nevada Reno), Gianluca Gregori (University of Oxford), Jongjin Kim (SLAC National Accelerator Laboratory), Maxence Gauthier (SLAC National Accelerator Laboratory), Chandra Curry (SLAC National Accelerator Laboratory), Benjamin Ofori-Okai (SLAC National Accelerator Laboratory), Christopher Schoenwaelder (SLAC National Accelerator Laboratory), Bob Nagler (SLAC National Accelerator Laboratory), Adrien Descamps (SLAC National Accelerator Laboratory), Giulio Monaco (University of Trento, Italy), Ulf Zastrau (European XFEL), Sebastian Goede (European XFEL), Rigby Alexandra (University of Oxford), Peihao Sun (SLAC National Accelerator Laboratory)
• 20:31
4.48 Velocity correction for nuclear activation detectors at the NIF 2h

The velocity distribution of the hotspot in an Inertial Confinement Fusion (ICF) implosion changes the spectra of fusion neutrons emitted from the experiment as a function of viewing angle. These velocity-induced spectral changes affect the response of nuclear activation detectors (NADs) positioned around the experiment, and must be accounted for to correctly extract information about areal density (ρR) asymmetry from the data. Three mechanisms through which average hotspot velocity affects NAD activation are addressed: change in activation cross-section due to Doppler shift of the mean neutron energy, kinematic increase in neutron fluence, and change in scattering cross-section due to Doppler shift. Using the hotspot velocity inferred from NTOF measurements of D-T and D-D fusion neutrons, the hotspot velocity is shown to account for 80% of the observed NAD activation asymmetry in a calibration shot with negligible fuel ρR. A robust method to evaluate uncertainties in spherical-harmonic fits to the NAD data due to the velocity correction and detector uncertainty is presented.

Speakers: Hans Rinderknecht (Lawrence Livermore National Laboratory), Richard Bionta (Lawrence Livermore National Laboratory), Hesham Khater (Lawrence Livermore National Laboratory), Gary Grim (Lawrence Livermore National Laboratory)
• 20:31
4.49 Polarisation-based suppression of background emission in visible light spectroscopy 2h

Contamination of plasma line emission by bright scattered background radiation poses a great challenge for spectroscopy-based diagnostics in metal wall machines such as ITER. It can be the case that the diffusely scattered background component will be largely unpolarised. This is because the light scattered from a roughened wall surface is the summation of light received from a range of incident angles and having varying degrees of polarisation, and polarisation states depending on the plasma emission properties and path integration effects. We propose and demonstrate the utility of polarisation sensitive spectral imaging for helping to separate the Zeeman-polarised local plasma emission (Stokes vector) from unwanted diffusely scattered background contamination. It has been shown recently that the Zeeman Stokes components can be related in a well-defined way to weighted line integrals of plasma flow and temperature in the case of Doppler effect spectroscopy. The weights depend on the local magnetic field structure. To explore these issues, we have installed an imaging polarimeter-interferometer for Doppler spectroscopy on the H-1 Heliac. We observe that background reflections dominate the unpolarized image but are largely absent in the polarised Stokes vector components.

Speaker: John Howard (Australian National University )
• 20:31
4.50 Streaked Backscatter Spectra of the Pre-Heat Laser on MagLIF Targets 2h

During magnetized liner inertial fusion (MagLIF) experiments at Sandia National Laboratories, a kJ class laser is used to pre-heat the deuterium fuel before compression. Laser-plasma-instabilities (LPI) result from the interaction of the high intensity laser with dense target materials such as the Laser-Entrance-Hole window, fuel and bottom-cap of the liner. The observed LPI scattering modes are stimulated Raman (SRS) and stimulated Brillouin (SBS). For parametric gain >20, these stimulated processes become parasitic and can block nearly all the laser pre-heat energy. Fortunately, we observe smaller gains. The total backscattered light is <10%. One benefit of observing some backscatter is that the wavelength shift and intensity can be used to diagnose the laser target interaction dynamics. SRS reveals the evolution of the electron plasma density. SBS indicates temperature. We will show how target and laser properties affect the time resolved backscatter spectra with comparisons to Hydra calculations. Sandia is a multi-mission laboratory managed and operated by National Technology and Engineering Solutions of Sandia, LLC, a wholly owned subsidiary of Honeywell International, Inc., for the U.S. Department of Energy’s NNSA under contract DE-NA0003525.

Speaker: David Bliss (Sandia National Laboratories)
• 20:31
4.51 Ultra Fast Charge Exchange Recombination Spectroscopy Detector Upgrade for Ion Turbulence Measurements 2h

A new actively cooled detector array and several recently implemented optimizations for the Ultra Fast Charge Exchange Recombination Spectroscopy (UF-CHERS) diagnostic on DIII-D have resulted in improved sensitivity to ion fluctuations. UF-CHERS measures carbon ion temperature (Ti) and toroidal velocity (v𝜙) fluctuations associated with long-wavelength turbulence and other plasma instabilities by observing the charge exchange (CX) reaction between injected Deuterium neutrals and intrinsic Carbon impurity with 1 μs time resolution and ~1 cm radial resolution. The upgrades resulted in a two-fold increase in signal levels and improved distinction between active CX and background emissions compared to a previous higher noise detector array, especially at the spectral line’s edge, which are critical for curve fitting with sparse wavelength bins (8 bins/channel). Ti and v𝜙 fluctuations up to ~230 kHz have been measured with the new array. The cross-phase of Carbon density and temperature (𝛥𝜙nC×Ti) associated with the Edge Harmonic Oscillations (EHO) in QH-mode, important to understanding increased energy confinement while allowing particle transport, were also measured. This work was supported by U.S. DOE grants DE-FG02-08ER54999, DE-FC02-04ER54698, and NSF GRFP grant DGE-1256259.

Speakers: Dinh Truong (University of Wisconsin - Madison), George McKee (University of Wisconsin - Madison), Zheng Yan (University of Wisconsin - Madison), Raymond Fonck (University of Wisconsin - Madison)
• 20:31
4.52 LaBr3 detectors for DD neutron yield measurements 2h

A LaBr3 scintillator-based neutron detection system has been tested at several neutron sources for evaluation as a DD neutron yield measurement. DD fusion neutrons (2.45 MeV) undergo (n,n’) reactions in Br-79m in the crystal, which then emits a 208 keV gamma ray that is detected. Because the gamma originates in the crystal, detection efficiency is high. In this work the detector was tested in three facilities: the National Ignition Facility (NIF) and two Dense Plasma Focuses (DPFs). By testing at different facilities, a linear response to yield confirmed the detector is suitable as a yield diagnostic for neutron fluences ranging from 1x10^3 to 1x10^5 n/cm^2. At NIF the response was cross-calibrated to NTOF yields. Later it was tested at a DPF, where it was compared to a He-3 detector. In the linear range of the He-3 detector the LaBr3 was proportional, although by a different constant due to the difference in neutron scattering between the DPF and NIF. A similar experiment was carried out at another DPF with higher yields. A block of Y, which has a higher activation energy threshold, was tested as a proof-of-concept at the high-yield DPF and had encouraging results.

Speakers: Ellen Edwards (LLNL), James Mitrani (LLNL), Yuri Podpaly (LLNL), Bruce Freeman (Verus Research), Manuel Alan (Verus Research), Charles Yeamans (LLNL), Andrea Schmidt (LLNL)
• 20:31
4.53 X-ray streaked Refraction Enhanced Radiography (RER) for inferring inflight ice-ablator density profiles of ICF capsule implosions 2h

In the quest for reaching ignition of deuterium-tritium (DT) fuel capsule implosions, experiments on the National Ignition Facility have shown lower final fuel areal densities than simulated. Possible explanations for reduced compression are higher preheat that can increase the ice-ablator density jump and induce ablator-DT ice mix, or reverberating shocks. We are hence developing x-ray Refraction Enhanced Radiography (RER) to infer the inflight density profiles in layered fuel capsule implosions. The RER uses a 5 µm imaging slit backlit by a Ni 7.8 keV He-alpha laser driven x-ray source at 20 mm from the capsule to cast refracted images of the inflight capsule onto a streak camera in a high magnification (M~60x) setup. Our first experiments have validated our setup using an un-driven high density carbon capsule that recorded a streaked RER x-ray fringe from the carbon ablator surface consistent with raytracing calculations at the required ~ 6 µm and 25 ps resolution for implosions. Streaked RER will be applied to inflight layered capsule implosions using a hydrogen-tritium fuel mix rather than DT to reduce neutron yields and associated x-ray backgrounds. This work was performed under the auspices of the U.S. Department of Energy by LLNL under Contract DE-AC52-07NA27344.

Speakers: Eduard Dewald (Lawrence Livermore National Laboratory), Otto Landen (Lawrence Livermore National Laboratory), Laurent Masse (Lawrence Livermore National Laboratory), Darwin Ho (Lawrence Livermore National Laboratory), Yuan Ping (Lawrence Livermore National Laboratory), Daniel Thorn (Lawrence Livermore National Laboratory), Nobuhiko Izumi (Lawrence Livermore National Laboratory), Laura Berzak Hopkins (Lawrence Livermore National Laboratory), Jeffrey Koch (NSTec)
• 20:31
4.54 Four-dimensional calibration turntable of the motional Stark effect diagnostic on EAST 2h

The motional Stark effect (MSE) diagnostic is applied to measure the safety factor q and current density profile of a tokamak device, which are important parameters in realizing the high-performance and long-pulse steady state of a tokamak. A single-channel MSE diagnostic based on photoelastic modulators (PEMs), whose sightline meets with the neutral beam injection at a major radius of R = 2.12 m, has been built for the D window of the Experimental Advanced Superconducting Tokamak (EAST). According to the requirements of MSE diagnostic polarimetric calibration, a high-precision four-dimensional calibration turntable, driven by four stepping motors and controlled by upper computer software, was designed for EAST. The turntable allows us to rapidly calibrate the MSE diagnostic in a series of positions and angles during EAST maintenance. The turntable can move in four dimensions of translation, yaw, pitch and roll of the polarizer, and can create linearly polarized light at any given angle with accuracy of ~0.05° for the MSE system offline calibration. Experimental results of the MSE diagnostic calibration in the laboratory show that the turntable has the advantages of high positioning accuracy, flexible spatial movement and convenient control.

Speakers: X. Huang (School of Electrical Engineering and Automation, Hefei University of Technology), D.M. Liu (School of Electrical Engineering and Automation, Hefei University of Technology), C. Liu (School of Electrical Engineering and Automation, Hefei University of Technology), J. Fu (Institute of Plasma Physics, Chinese Academy of Sciences), B.N. Wan (Institute of Plasma Physics, Chinese Academy of Sciences), B. Lu (Institute of Plasma Physics, Chinese Academy of Sciences), Z.W. Wu (Institute of Plasma Physics, Chinese Academy of Sciences), C.T. Holcomb (Lawrence Livermore National Laboratory), J. Ko (National Fusion Research Institute), W.L. Rowan (Institute for Fusion Studies, The University of Texas at Austin), H. Huang (Institute for Fusion Studies, The University of Texas at Austin), G.Z. Miao (School of Electrical Engineering and Automation, Hefei University of Technology)
• 20:31
4.55 Spectral and intensity calibration of a Thomson scattering diagnostic for the C-2W field-reversed configuration plasma experiment 2h

The C-2W Thomson Scattering diagnostic consists of two individual systems for monitoring electron temperature and density; one system in the central region is operational and the second system, currently under design, will monitor the open field line jet region [1]. The laser and collection optics for this diagnostic will be described separately [2]. A broadband source and a scanning monochromator have been setup for the spectral calibration of the polychromators. The system intensity calibration is performed using Rayleigh scattering with the vessel filled with argon gas at different pressures. This paper will detail the design principles and results of the spectral channel configurations, signal conditioning of the polychromators and their spectral calibrations, and the Rayleigh scattering calibration for the whole system response. [1] K. Zhai Thomson scattering systems on C-2W field-reversed configuration plasma experiment HTPD 2018 [2] A. Ottaviano Characterization of system components for Thomson scattering diagnostics on C-2W HTPD 2018

Speakers: Tania Schindler (TAE Technologies, Inc.), Kan Zhai (TAE Technologies, Inc.), Angelica Ottaviano (TAE Technologies, Inc.), Matt Thompson (TAE Technologies, Inc.)
• 20:31
4.56 Measurement of electron temperature fluctuation on the J-TEXT tokamak via correlation ECE 2h

Anomalous transport is a key issue to affect the confinement properties of plasma. Turbulence measurement is important for the study of anomalous transport. An eight-channel correlation electron cyclotron emission (CECE) system has been developed based on the existing conventional electron cyclotron emission (ECE) radiometer for the measurement of electron temperature fluctuation on the Joint-Texas Experimental (J-TEXT) tokamak. The signal received by the ECE radio frequency (RF) unit is split and fed to the CECE system. Then the signal is resolved by 8 narrow band-pass filters including six YIG filters and two fixed frequency filters. The electron temperature fluctuation at four separate radial positions can be measured by coherences analysis. With an focused lens unit, this system can measure temperature fluctuations which have k_θ≤2.5cm^(-1). Based on the CECE system, some interesting phenomena of electron temperature fluctuations have been observed on J-TEXT.

Speakers: Zhoujun Yang (Huazhong University of Science and Technology), Hao Zhou (Huazhong University of Science and Technology), Xiaoming Pan (Huazhong University of Science and Technology), Xianli Xie (Huazhong University of Science and Technology), Bowen Ruan (Huazhong University of Science and Technology)
• Tuesday, 17 April
• 07:00 08:15
Breakfast
• 08:30 10:30
Session #5, Tuesday Morning Invited Talks, Chair T. Hilsabeck
• 08:30
5.1 Absolute Calibration of a Time-Resolved High Resolution X-ray Spectrometer for the National Ignition Facility 30m

A high resolution, Diagnostic-Instrument-Manipulator-based x-ray Bragg crystal spectrometer has been calibrated for and deployed at the National Ignition Facility (NIF) to diagnose plasma conditions and mix in ignition capsules near stagnation times. The spectrometer has two conical crystals in the Hall geometry focusing rays from the Kr He-α and He-β complexes onto a streak camera, with the physics objectives of measuring time-resolved electron density and temperature through observing Stark broadening and the relative intensities of dielectronic satellites. A third von Hámos crystal time-integrates the intervening energy range to provide in-situ calibration for the streak camera signals. The spectrometer has been absolutely calibrated using a microfocus x-ray source, an array of CCD and single-photon-counting detectors, and multiple K- and L-absorption edge filters. Measurements of the integrated reflectivity, energy range, and energy resolution for each crystal will be discussed. Spectra and images from a polar direct-drive exploding pusher target on NIF will be shown, with absolute intensity determined by pre-shot calibration. This work was performed under the auspices of the US DoE by PPPL under DE-AC02-09CH11466 and by LLNL under DE-AC52-07NA27344.

Speakers: Lan Gao (Princeton University), presented by Brian F. Kraus (Princeton University), Kenneth W. Hill (Princeton Plasma Physics Laboratory), Manfred Bitter (Princeton Plasma Physics Laboratory), Philip C. Efthimion (Princeton Plasma Physics Laboratory), Marilyn B. Schneider (Lawrence Livermore National Laboratory), Andrew G. MacPhee (Lawrence Livermore National Laboratory), Daniel B. Thorn (Lawrence Livermore National Laboratory), Joseph Kilkenny (General Atomics), Jay Ayers (Lawrence Livermore National Laboratory), Robert Kauffman (Lawrence Livermore National Laboratory), Hui Chen (Lawrence Livermore National Laboratory), David Nelson (University of Rochester Laboratory for Laser Energetics)
• 09:00
5.2 Derivation of a 3D volume in highly distorted ICF implosions from multiple line-of-sight imaging 30m

Estimating the volume of a highly distorted ICF core is critical to evaluating the performance of an ICF implosion: degree of alpha heating is inferred from hot spot pressure, which is in turn derived from hot spot volume, as observed from x-ray self-emission images. Accurate tomographic reconstruction to determine volume is precluded by the limited number of accessible lines of sight (typically two). Moreover, due to dynamically evolving temperature and density gradients, hot spot boundaries are difficult to define and thus to observe. Approximations using spherical or elliptical assumptions have been shown to over-predict the volume significantly. We describe a method to infer volumes of asymmetric shapes using orthogonal images and emission intensity with no assumption of symmetry or critical contour. An ensemble of simulated images was used to validate the method, and application of the technique to recent NIF implosions has revealed trends in time-dependent volume that provide insights into stagnation dynamics. This work also provides a tool for quantifying the amount of material that jets into the hot spot via engineering features -- a leading hypothesis for the underperformance of ICF implosions. Prepared by LLNL under Contract DE-AC52-07NA27344, LLNL-ABS-744386.

Speakers: Laura Robin Benedetti (LLNL), S. R. Nagel (LLNL), T. Ma (LLNL), S. F. Khan (LLNL), A. Pak (LLNL), N. Izumi (LLNL)
• 09:30
5.3 Prospects of X-ray Imaging Spectrometers for Impurity Transport: Recent Results from the Stellarator Wendelstein 7-X 30m

X-ray imaging spectrometers are used on many fusion experiments for the measurement of basic plasma parameters, such as ion and electron temperatures Ti and Te, impurity densities nZ, plasma flow velocities v and recently also for the determination of the radial electric field Er .This paper shows initial measurements of the recently upgraded X-ray imaging spectrometer systems XICS and HR-XIS which are installed at the optimized stellarator Wendelstein 7-X. Both spectrometers are designed to detect impurity emission of highly ionized charge states for various impurities, such as Si, Ar, Ti, Fe, or Mo. In combination with a laser blow-off system, spatio-temporal impurity emissivities were measured by the spectrometers, giving access to the impurity confinement times and allowing for the determination of diffusive and convective transport parameters D and v. Specific settings of the power deposition reveal a significant impact on impurity confinement time, possibly driven by changes in the radial electric field. Experimental findings are compared to neoclassical theory and modeled with the 1D transport analysis code STRAHL.

Speakers: Andreas Langenberg (Max-Planck-Institut für Plasmaphysik), Novimir Pablant (Princeton Plasma Physics Laboratory), Thomas Wegner (Max-Planck-Institut für Plasmaphysik), Peter Traverso (Auburn University), Oleksandr Marchuk (Institut für Energie und Klimaforschung-IEK-4), Benedikt Geiger (Max-Planck-Institut für Plasmaphysik), Birger Buttenschoen (Max-Planck-Institut für Plasmaphysik), Andrea Pavone (Max-Planck-Institut für Plasmaphysik), Jakob Svensson (Max-Planck-Institut für Plasmaphysik), Arturo Alonso (Laboratorio Nacional de Fusión), Daihong Zhang (Max-Planck-Institut für Plasmaphysik), Rainer Burhenn (Max-Planck-Institut für Plasmaphysik), Albert Mollen (Max-Planck-Institut für Plasmaphysik), Robert Wolf (Max-Planck-Institut für Plasmaphysik)
• 10:00
5.4 Sub-nanosecond Single Line-of-Sight (SLOS) X-ray Imagers 30m

A new generation fast-gated x-ray framing cameras has been developed that is capable of capturing multiple frames along a single line-of-sight with 25 ps temporal resolution and 40 μm spatial resolution. This was achieved by integrating an electron pulse-dilation imager [1] with Sandia’s nanosecond-gated burst mode CMOS sensors [2]. The combination of these two transformative technologies enables a new class of x-ray imagers that will have significant impact in HED diagnostic applications requiring high temporal and spatial resolution. The first of these instruments, SLOS-TRXI and SLOS-CBI, have been deployed at the Omega and NIF HED facilities and began on-line commissioning in the Fall of 2016. Here we present the system architecture, as well as system characterization and performance. We will discuss in detail the testing performed to tune the photocathode voltage waveform, which achieves a uniform temporal magnification profile, as well as the implications for the systems’ dynamic range and sensitivity. Finally, we will present design improvements for future instruments aimed at mitigating space-charge broadening to improve the dynamic range and compensating for the electron energy chirp to provide uniform temporal sensitivity.

Speakers: Kyle Engelhorn (General Atomics), Terance Hilsabeck (General Atomics)
• 10:30 12:31
Session #6, Tuesday Morning Poster Session
• 10:30
6.1 Relative Intensity Calibration of the DIII-D Charge-Exchange Recombination Spectroscopy System Using Neutral Beam Injection into Gas 2h

A new calibration method for the DIII-D charge-exchange spectroscopy system produces smoother impurity density profiles compared to previous techniques, improving the accuracy of our impurity density profile reconstruction. Relative intensity calibration between the chords of the DIII-D charge-exchange recombination (CER) spectroscopy system is performed by firing neutral beams into the evacuated vacuum vessel pre-filled with neutral gas. Relative calibration is required to account for uncertainty in the 3D geometry of the neutral beam. Previous methods using helium gas have been improved by using xenon, which emits an emission line close to the commonly used carbon wavelength 5290.5A, as well as improved timing of the gas injection, inclusion of variation in the vessel pressure, and timing of neutral beam injection. Photoemission recorded by 108 sightlines viewing 6 neutral beams are compared and used to form a relative calibration factor for each sightline. This relative calibration is used to refine the absolute intensity calibration procedure that utilizes an integrating sphere. Results of the relative calibration are compared to an ideal diverging beam calculation that uses a Monte-Carlo 3D model and exposes discrepancies in the assumptions about the neutral beam divergence.

Speakers: B. A. Grierson (Princeton Plasma Physics Laboratory), S.R. Haskey (Princeton Plasma Physics Laboratory), Colin Chrystal (General Atomics), K. H. Burrell (General Atomics)
• 10:30
6.2 Design of shattered pellet injection system and diagnostics capability on J-TEXT 2h

Disruptions have the potential to cause severe material wall damage to large tokamaks like ITER. The mitigation of disruption damage is essential for the safe operation of large scale tokamak. The shattered pellet injection(SPI) technique, which is regarded as the primary injection method in ITER, has been show several advantages relative to massive gas injection, including more rapid particle delivery, higher total particle assimilation and more centrally peaked particle deposition. A dedicated argon SPI system focus on disruption mitigation and runaway current dissipation experiment has been being designed for the J-TEXT tokamak. It will be put into disruption experiment in next year. The pellet will be cooled by a refrigerator to about 80K. The pellet can be shaped with 5 mm diameter and 4-10 mm length. Helium gas at room temperature will be used as a propellant gas for pellet acceleration. The pellet can be injected with speed of 150-300m/s. The time interval between injection cycles is about 8 minutes. The pellet will be shattered at edge of the plasma with the speed of 150-200m/s and then injected into the core of plasma. Related diagnostics for the disruption mitigation experiment by the SPI is presented.

Speakers: You Li (Huazhong University of Science and Technology), Zhongyong Chen (Huazhong University of Science and Technology), Zoujun Yang (Huazhong University of Science and Technology)
• 10:30
6.3 Multipoint vertical-Thomson scattering diagnostic on HL-2A tokamak 2h

Some progress has been made to develop multipoint Thomson scattering diagnostic on HL-2A tokamak. Hardware of Si-APD detector electronics is improved, which provides two output signal channels. In one channel, only the rapid TS signal is output after deducting the influence of background slow-varying plasma light. In the other, both the rapid TS signal and the plasma background signal are output. In last HL-2A experiment campaign, the newly developed electronics are tested and TS signals can be obtained from each of the two channels, where the signal is digitized by 12-bit transient recorder sampled at 1GS/s. Laser beam alignment is fulfilled by using motorized stages to control the laser beam pass through ~10 mm-wide narrow throats of the lower and upper closed divertors with small movements, then strayed laser light is reduced. New modules of fast digtizers with more than 100 channels are installed and will be used to record TS pulse signals. On the basis of these achivements, about 20-point measurements of plasma Te and ne by Thomson scattering diagnostic will come into operation in this HL-2A experiment campaign.

Speaker: Yuan Huang (Southwestern Institute of Physics)
• 10:30
6.4 Implementing time resolved hot spot electron temperature capability on NIF using a streak camera 2h

The electron temperature (Te) of the hot spot within the core of imploded ICF capsules is an effective indicator of implosion performance. Currently, we have spatially and temporally integrated Te inferences using image plates. A temporally resolved measurement of Te will help elucidate the mechanisms for hot spot heating and cooling such as conduction to fuel, alpha-heating, mix and radiative losses. To determine the temporally resolved Te of hot spots, specific filters are added to an existing x-ray streak camera “Streaked Polar Instrumentation for Diagnosing Energetic Radiation (SPIDER)” to probe the emission spectrum during the x-ray burn history of implosions. One of the difficulties in inferring the hot spot Te is the attenuation of the emission due to opacity from the shell and fuel. A series of increasingly thick titanium filters were therefore used to select an x-ray band which reduces the influence of the shell/fuel optical depth while maintaining sensitivity to temperature. The signal level of the emission through the thicker filters are relatively poor so a dual slit (aperture) was designed to increase detected signal at the higher end of the spectrum. Herein, the design of the filters and slit and expected accuracy are described, and initial Te results are reported.

Speakers: Shahab Khan (LLNL), Leonard Jarrott (LLNL), Pravesh Patel (LLNL), Nobuhiku Izumi (LLNL), Tammy Ma (LLNL), Andrew MacPhee (LLNL), Benjamin Hatch (LLNL), Otto Landen (LLNL), Joseph Kilkenny (General Atomics), David Bradley (LLNL)
• 10:30
6.5 Study of the acid phthalates (01l), l<10, crystal reflections for quantitative spectroscopic studies 2h

Acid phthalates crystals such as KAP crystals are the method of choice to record x-ray spectra in the soft x-ray regime (E~1keV) using the large (001) 2d=26.63Å spacing. Burkhalter et al., J. Appl. Phys., 1981, showed that (013) reflection is about or more reflective as the 2nd order reflection (002) and can even overlap the main first order reflection when the crystal b-axis is contained in the dispersion plane, thus contaminating the main (001) measurement. In general, (01l) l≤10, reflections have comparable reflectivity as their respective (00l) counterparts and coincides with the (001) reflection at the limit of l large. We studied the (01l) reflection when the crystal b-axis is parallel and perpendicular to the dispersion plane for different spectral ranges. We discuss the effect of contamination of these reflections and potential applications for quantitative spectroscopy. ++ Sandia National Laboratories is a multimission laboratory managed and operated by National Technology and Engineering Solutions of Sandia LLC, a wholly owned subsidiary of Honeywell International Inc. for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-NA0003525.

Speaker: Patrick Lake (Sandia National Laboratories)
• 10:30
6.6 Study of electron temperature fluctuation evolution with upgraded ECE Imaging on DIII-D 2h

A new generation of millimeter-wave heterodyne imaging detector arrays has been developed with liquid crystal polymer (LCP) substrate modules and demonstrated on the DIII-D ECEI system. These arrays exhibit ~ 15 dB additional gain and > 30x reduction in noise temperature compared to the previous generation and provide ECEI capability for absolute electron temperature calibration. In each LCP horn-waveguide module, a 3x3 mm GaAs MMIC (Monolithic Microwave Integrated Circuit) chip, consisting of a low noise amplifier (LNA), balanced mixer, local oscillator multiplier chain and IF amplifier, was employed to generate LO with ~12 GHz input via an RF cable to the enclosure box. A proof-of-principle instrument with 5 poloidal channels was installed on DIII-D in 2017. The full system installation (20 poloidal channels) is scheduled for early in 2018. The LCP ECEI system is used for pedestal region measurements, especially focusing on temperature evolution during ELM bursting. The DIII-D ECEI signal has been significantly improved with extremely effective shielding of out-of-band microwave noise. In H-mode ELM bursting, the radial propagation of electron heat flow has been detected on DIII-D. The LCP ECEI is expected to be a valuable diagnostic tool for ELM physics investigations.

Speakers: Yilun Zhu (UC Davis), Yu Ye (UC Davis), Jo-han Yu (UC Davis), Benjamin Tobias (LANL), Anh-Vu Pham (UC Davis), Yan Wang (UC Davis), Chen Luo (UC Davis), Calvin Domier (UC Davis), Gerrit Kramer (PPPL), Ahmed Diallo (PPPL), Yang Ren (PPPL), Ming Chen (UC Davis), Raffi Nazikian (PPPL), Neville Luhmann (UC Davis)
• 10:30
6.7 Development of Passive Vibration Isolator for the Interferometers on KSTAR 2h

Laser interferometry, as one of the important plasma diagnostic systems on the magnetic fusion devices, suffers from vibration-induced noise. Advanced tokamak interferometers utilize technology that is intrinsically free from vibration-induced noise such as two-color interferometer or dispersion interferometer. However, data analysis of Two Color Interferometer (TCI) on KSTAR showed that the removal of vibration on the retro-reflectors will improve the quality of TCI diagnostics. A passive vibration isolator based on the mass-spring system is developed for the interferometers on KSTAR. The new vibration isolator can be used for the vertical beam coming out from bottom in the strong magnetic field. Comparison of line integrated density data from the Far Infrared Interferometer with vibration isolator and without vibration isolator indicated that 98% of vibrational noise is removed. In addition, the design of a compact passive vibration isolator for the in-vessel installation will be presented.

Speaker: Kwan Chul Lee (NFRI)
• 10:30
6.8 Polycapillary optics for Soft X-Ray transmission in ITER 2h

Tokamak plasmas emit as a volumetric Soft X-Ray (SXR) source and the emitted radiation contains very useful information about plasma stability, shape and impurity content. In the deuterium-tritium phase of ITER, the high neutron fluxes, gamma and hard X-ray emission will constitute too harsh an environment to permit the use of classical semiconductor detectors in a close vicinity of the machine. The first issue is thus to consider new SXR detector technologies more robust to such environments. The GEM (Gas Electron Multiplier) and LVIC (Low Voltage Ionization Chamber) are foreseen as the two most promising solutions so far. The second issue is then to investigate the possibility of moving these detectors at a sufficient distance from the plasma to protect them from heat fluxes and radiation. We have thus investigated the possibility of using polycapillary lenses in ITER, to transport the SXR information several meters away from the plasma in the complex port-plug geometry. Different polycapillary lenses configurations have been tested thanks to a polycapillary transmission model and synthetic diagnostics (mimicking GEM and LVIC response) which have been recently developed. Results confirm the great potential of polycapillary lenses for SXR transmission in tokamak plasmas.

Speakers: Didier MAZON (CEA), Sabastien TOURENQ (IMT Atlantique), Damien COLETTE (CEA), Robin BARNSLEY (ITER), Martin O'MULLANE (University of Strathclyde), Antoine SIRINELLI (ITER), Michael WALSH (ITER), Axel JARDIN (CEA)
• 10:30
6.9 Synthetic Diagnostic for Assessing Spatial Averaging of Charge Exchange Recombination Spectroscopy Measurements 2h

A synthetic charge exchange recombination spectroscopy diagnostic based on the FIDAsim modeling suite has been created for the DIII-D tokamak. This synthetic diagnostic assumes the ions have Maxwellian distribution functions on each flux surface and generates synthetic emission from charge exchange events between the beam neutrals and a fully ionized impurity. This work was motivated by the observation of non-Gaussian spectra that may be caused by spatial averaging, atomic physics, or non-Maxwellian distribution functions. Measurements of non-Gaussian spectra commonly observed in the H-mode pedestal and in plasmas with very steep core gradients are compared to the synthetic diagnostic. Spatial averaging alone cannot account for the observations, indicating other cause(s) such as non-Maxwellian distribution functions. The synthetic diagnostic has also been used to resolve a long-standing issue: it is shown that vertical view chords near the magnetic axis often measure lower temperatures than the tangential view chords because of a difference in spatial averaging due to the DIII-D neutral beams being twice as tall as they are wide. Work supported by US DOE under DE-FC02-04ER54698, DE-AC02-09CH11466, and the Science Undergraduate Laboratory Internship (SULI) program.

Speakers: Colin Chrystal (General Atomics), Alex Sulyman (University of California Davis), Shaun Haskey (Princeton Plasma Physics Laboratory), Keith Burrell (General Atomics), Brian Grierson (Princeton Plasma Physics Laboratory)
• 10:31
6.10 Inverse estimate of the perturbation current density profile of the interchange mode from the magnetic probe measurement in LHD 2h

In order to evaluate the effect of the MHD instabilities, estimate of the shape the eigenfunction of the MHD mode is necessary. It is not easy to estimate from the magnetic field data measured by the Mirnov coil arrays since the magnetic fluctuation signal is integrated from the perturbation currents inside the plasma. It is a kind of ill-posed inverse problem. However, in the case of the interchange mode where the eigenfunction is quite localized on the rational surface, perturbation current profile perpendicular to the magnetic field line may be estimated from the magnetic fluctuation data. From the numerical test assuming that the current density is localized on the rational surface, the inverse estimate of the current density profileis found to be possible if the suitable regularization method, such as L2-regularization, is used for solving the inverse problem. LHD is a Heliotron type device where net toroidal current is small. Pressure driven mode, such as the interchange mode is the dominant MHD instabilities. Quite deformed waveform, different from the sinewave, are often observed in experiments. Methods for solving the inverse problem and the estimate of the parallel current density profile of complicated MHD phenomena is presented.

Speaker: Satoshi Ohdachi (National Institute for Fusion Science)
• 10:31
6.11 High temperature measurement using Neon-like Xenon lines on X-ray crystal spectrometers on EAST 2h

A two-crystal spectrometer system has been implemented in the EAST tokamak to simultaneously measure high- and low-temperature plasma regions using He- and H-like Argon spectra. But for future devices like ITER and CFETR, the Ar ions become fully stripped and the intensity of the H-like lines weaken significantly at high temperatures (Te>5 keV). With increasing auxiliary heating power on EAST, the core plasma temperature could also reach 5 keV and higher. In such conditions, the use of a Xenon puff becomes an appropriate choice for both ion-temperature and flow-velocity measurements. A new two-crystal system using a He-like Ar crystal (2d=4.913 Å) and a Ne-like Xe crystal (2d=6.686 Å) has been deployed on a poloidal XCS spectrometer. While the He-like Argon spectra will be used to measure the plasma temperature in the edge plasma region, the Ne-like Xenon spectra will be used for measurement in the hot core. The new crystal arrangement allows a wide temperature measurement ranging from 0.5 to 10 keV or even higher, being the firsts tests for burning plasmas like ITER and CFETR. Preliminary result of lab-tests, Ne-like Xenon lines measurement and a new calibration procedure using a Ti x-ray tube will be presented.

Speakers: Bo Lyu (Institute of Plasma Physics, Chinese Academy of Sciences), Jun Chen (School of Nuclear Science and Technology, University of Science and Technology of China), Luis Delgado-Aparicio (Princeton Plasma Physics Laboratory), Qiuping Wang (National Synchrotron Radiation Laboratory, University of Science and Technology of China), Xuewei Du (National Synchrotron Radiation Laboratory, University of Science and Technology of China), Jin Shen (National Synchrotron Radiation Laboratory, University of Science and Technology of China), Xinshuai Yang (Institute of Plasma Physics, Chinese Academy of Sciences), Fudi Wang (Institute of Plasma Physics, Chinese Academy of Sciences), Jia Fu (Institute of Plasma Physics, Chinese Academy of Sciences), Yingying Li (Institute of Plasma Physics, Chinese Academy of Sciences), Manfred Bitter (Princeton Plasma Physics Laboratory), Kenneth Hill (Princeton Plasma Physics Laboratory), Songgon Lee (National Fusion Research Institute), Yuejiang Shi (Department of Nuclear Engineering, Seoul National University), Baonian Wan (Institute of Plasma Physics, Chinese Academy of Sciences), Minyou Ye (School of Nuclear Science and Technology, University of Science and Technology of China)
• 10:31
6.12 Dual-laser wavelength Thomson scattering at Wendelstein 7-X 2h

The Thomson scattering (TS) system is a main diagnostic at the Wendelstein 7-X stellarator for electron temperature (Te) and density (ne) profiles. The TS system includes a pulsed, high power Nd:YAG laser with λ=1064 nm, together with five interference filter polychromators for spectral analysis of the scattered light in the near infrared region between λ=750-1061 nm. The system is able to measure Te up to approximately 10 keV within an error of ~10%, depending on ne and background light. The system will be equipped with an additional Nd:YAG laser with λ=1319 nm, so that the peak of the TS spectrum shifts up by 1319-1064=255nm. This has two advantages: First, the dual laser availability allows an in-situ spectral calibration, based on the two lasers being fired quasi-simultaneously; the two measured TS spectra, covering different wavelength regions, should yield an unchanged Te. Secondly, higher Te >10 keV can be measured as the peak of the TS spectrum shifts to shorter wavelengths. This avoids the polychromators having to cover λ<750 nm, where line emission and Bremsstrahlung increase strongly. The status of the 1319 nm Nd:YAG laser development and the design of optical components of the laser beam path will be shown and simulations will demonstrate the new system capabilities.

Speakers: Ekkehard Pasch (Max-Planck-Institut für Plasmaphysik), Marc Beurkens (Max-Planck-Institut für Plasmaphysik), Sergey Bozhenkov (Max-Planck-Institut für Plasmaphysik), Golo Fuchert (Max-Planck-Institut für Plasmaphysik), Robert Wolf (Max-Planck-Institut für Plasmaphysik)
• 10:31
6.13 A combined mmwave and CO2 interferometer on the C-2W Jet plasma 2h

The C-2W device at TAE Technologies is now operational and represents another major step in a progression of advanced beam-driven Field-Reversed Configuration (FRC) confinement devices that have prolonged the lifetime, increased the stability and have added significant neutral beam injection power to heat and sustain an FRC plasma. Crucial to plasma sustainment and increased lifetime is an understanding of the Jet plasma and X-point dynamics. A novel two-color multi-chord tangentially viewing interferometer has been designed and built to provide line averaged density at both 10.6 mm mid-infra-red and 1000 mm millimeter-wave wavelengths. This combination of sources allows a generous measurement dynamic range. The Jet interferometer is positioned in the mirror region of the confinement vessel (CV) to capture the initial high-density translated FRC source, the establishment of the Jet outflow from the merging of the two FRCs in the CV and the steady-state Jet plasma for the duration of the discharge which is expected to be of low line averaged density. An array of four tangential chords is anticipated to allow some profile reconstruction. Discussion of the performance and data will be presented.

Speakers: Roger J Smith (TAE Technologies, Inc.), TAE Team
• 10:31
6.14 System Level Design of the ITER Bolometer Port Plug Cameras 2h

The ITER bolometer diagnostic is planned to have 550 lines of sight (LOS) distributed all over the vessel. 240 channels are provided by cameras mounted in two Upper Ports and in one Equatorial Port. This paper describes the current status of the system level design of the port cameras and the solutions proposed how to implement all required camera components while meeting a multitude of competing requirements. Sensor holders, support structures and different apertures depending on the camera type (pinhole or collimator), cable connectors, ceramic track plates and many mineral insulated cables have to be integrated within a restricted space envelope to guarantee functionality. The impact of the interface requirements agreed with the port integrator, such as the mechanical mounting interface, the electrical interface and the load specifications, on the design flexibility will be discussed. Using the example of an Upper Port camera with 60 LOS, the assembly of the camera components is explained and two currently discussed architecture options of the RH-maintenance scheme in the hot cell are compared. Finally, considerations on a cost-effective design of the track plates and design optimizations based on thermal finite element analysis of the camera are presented.

Speakers: Florian Penzel (Max Planck Institute for Plasma Physics), Hans Meister (Max Planck Institute for Plasma Physics), Dieter Hermann (Max Planck Institute for Plasma Physics), Adam Pataki (Max Planck Institute for Plasma Physics), Eric Walcz (Wigner Research Centre for Physics), Levente Tatar (Centre for Energy Research, Hungarian Academy of Sciences), Gabor Nadasi (Wigner Research Centre for Physics), Zoltán Szabó-Bálint (Wigner Research Centre for Physics), Ulrich Walach (Fusion for Energy), Lars Christian Ingesson (Fusion for Energy), Roger Reichle (ITER Organization), Jose Sanchez (ITER Organization)
• 10:31
6.15 Fiber-Optic Pulsed Polarimetry Measurements of DIII-D Poloidal Field 2h

Fiber optic pulsed polarimetry (FOPP) measures the magnetic field along an optical fiber by detecting changes in the direction of the polarization of laser light propagating through the fiber due to the Faraday effect. By observing the backscatter light as a function of time from specially prepared fibers with weak fiber Bragg gratings, it is possible to obtain both the time and spatial dependence of the field along the fibers. Single-mode optical fibers were installed in the poloidal direction on the outside of the thermal blanket on DIII-D. Light at 532 nm from a mode-locked Nd:YAG laser was injected into the optical fibers. The laser repetition rate was 895 MHz with a pulse length of <10 ps. The backscatter light was detected by high-speed avalanche photodiodes. Bandwidth limitations of the detectors resulted in a spatial resolution of approximately 2 cm. The detector system measures the Stokes components necessary to determine changes in the polarization of the backscattered light. A non-uniform spatial distribution of the poloidal field that varies during the shot is observed. The results will be compared with existing inductive probe data.Work supported by US DOE under Award No. DE-SC0009808 and DE-FC02-04ER54698.

Speakers: Wayne Kimura (STI Optronics, Inc.), Dilraj Dhillon (STI Optronics, Inc.), Edward Strait (General Atomics), Stefano Munaretto (General Atomics), Detao Du (General Atomics), Sebastien Loranger (Polytechnique Montreal), Jean-Sebastien Boisvert (Polytechnique Montreal), Raman Kashyap (Polytechnique Montreal)
• 10:31
6.16 Design of Langmuir probe diagnostic system for the upgraded lower tungsten divertor in EAST tokamak 2h

In order to achieve long-pulse H-mode plasma scenario over 400s with high heating power in the Experimental Advanced Superconducting Tokamak (EAST) device, the lower graphite divertor will be upgraded into tungsten (W) divertor with active water cooling, which consists of the W monoblocks as divertor targets and the flat-type W/Cu plasma facing components (PFCs) as the divertor dome and baffles. As a typical diagnostic tool, the divertor Langmuir probe (DivLP) diagnostic system will also be upgraded accordingly. This paper presents the design of two kinds of newly DivLP systems, which are planned to be utilized on the W monoblock assembly parts and the flat-type W/Cu assembly parts for the lower tungsten divertor, respectively, in terms of their structures and preliminary toroidal and poloidal layouts. The DivLP system can measure the steady-state and transient plasma parameters with the schemes of triple-probe, double-probe and single-probe, to obtain the spatial and temporal distribution of plasma on the divertor PFCs, which is useful for the discharge controlling and operation in EAST. In addition, the thermal finite element analysis of the two kinds of probes is also carried out by using three-dimensional (3D) finite element code ANSYS, which aimed to get the optimal designs.

Speakers: Jichan Xu (Institute of Plasma Physics, Chinese Academy of Sciences(ASIPP)), Liang Wang (Institute of Plasma Physics, Chinese Academy of Sciences(ASIPP)), Guosheng Xu (Institute of Plasma Physics, Chinese Academy of Sciences(ASIPP)), Hai Xie (Institute of Plasma Physics, Chinese Academy of Sciences(ASIPP)), Wei Feng (Institute of Plasma Physics, Chinese Academy of Sciences(ASIPP); 2.University of Science and Technology of China(USTC)), Jianbin Liu (Institute of Plasma Physics, Chinese Academy of Sciences(ASIPP)), Guozhong Deng (Institute of Plasma Physics, Chinese Academy of Sciences(ASIPP); 2.University of Science and Technology of China(USTC)), Damao Yao (Institute of Plasma Physics, Chinese Academy of Sciences(ASIPP)), Guangnan Luo (Institute of Plasma Physics, Chinese Academy of Sciences(ASIPP)), Houyang Guo (Institute of Plasma Physics, Chinese Academy of Sciences; General Atomics, PO Box 85608, San Diego, CA 92186, USA)
• 10:31
6.17 Extracting the turbulent flow-field using velocimetry analysis 2h

Velocimetry analysis of density turbulence images obtained with beam emission spectroscopy (BES) on DIII-D is used to infer the 2D turbulent flow-field. The BES system on DIII-D obtains low-wavenumber density fluctuation images using an 8x8 grid of channels in the radial-poloidal plane with ≈1 cm spatial resolution and 1 μs sampling rate. The time-resolved 2D turbulent flow-field is obtained by spatiotemporally interpolating the limited resolution images and then applying an orthogonal dynamic programming (ODP) algorithm [1]. The algorithm is a frame-to-frame matching technique that works by using a global minimization method to determine which velocity vector maps one frame to another. In this work, the accuracy and uncertainty of the ODP algorithm applied to BES data is assessed using density and electrostatic potential fluctuation data from higher spatial resolution nonlinear gyrokinetic GENE simulations by comparing the velocimetry-estimated flow-field to the true ExB flow-field. Algorithm parameters, including search domain and spatiotemporal interpolation, are scanned to determine optimal values for most accurately estimating flow velocities.Supported by US DOE under Award No. 3DE-SC0001288, DE-FG02-08ER54999, and DE-FC02-04ER54698. [1] G. McKee et al, RSI 75 3490 (2004)

• 10:31
6.18 Engineering design for Wolter imaging diagnostic on Z 2h

Wolter optics are a mature imaging technology, although they are new to Sandia’s Z machine pulsed-power accelerator. Wolter optics have a number of physics performance advantages over more traditional imaging technologies like pinholes and slits; however they require careful design and precise alignment to reduce data analysis uncertainties. This paper discusses the mechanical engineering and design of the Z Wolter optic system. Meeting the 500 µm source-to-optic distance tolerance requirement was a significant challenge since this relationship can only be measured indirectly, under vacuum, and is approaching the accuracy limit of available commercial off-the-shelf rangefinders. The devised solution locates a precision switch with tightly toleranced mechanical components. A Monte Carlo simulation was performed to quantify the system level contributions of the Wolter optic alignment stage motion control uncertainties, which demonstrated 1σ requirements compliance. Sandia National Laboratories is a multimission laboratory managed and operated by National Technology and Engineering Solutions of Sandia, LLC., a wholly owned subsidiary of Honeywell International, Inc., for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-NA-0003525.

Speakers: Christopher Ball (Sandia National Laboratories), David Ampleford (Sandia National Laboratories), Paul Gard (Sandia National Laboratories), Maurer Andrew (Sandia National Laboratories), Christopher Bourdon (Sandia National Laboratories), Jeffrey Fein (Sandia National Laboratories), Ming Wu (Sandia National Laboratories), Lake Patrick (Sandia National Laboratories), Linda Nielsen-Weber (Sandia National Laboratories), Gregory Dunham (Sandia National Laboratories), Drew Johnson (Sandia National Laboratories), Owen Johns (Sandia National Laboratories), Bernard Kozioziemski (Lawrence Livermore National Laboratory), Louisa Pickworth (Lawrence Livermore National Laboratory), Julia Vogel (Lawrence Livermore National Laboratory), Mike Pivovaroff (Lawrence Livermore National Laboratory), Christopher Walton (Lawrence Livermore National Laboratory), Jay Ayers (Lawrence Livermore National Laboratory), Perry Bell (Lawrence Livermore National Laboratory), Brian Ramsey (NASA Marshall Space Flight Center), Suzanne Romaine (Harvard-Smithsonian Center for Astrophysics)
• 10:31
6.19 Conceptual design of extended magnetic probe set to improve 3D field detection in NSTX-U 2h

Adding toroidal arrays of magnetic probes at the top and bottom of NSTX-U would improve both the detection of the multimodal plasma response to applied magnetic perturbations and the identification of the poloidal structure of unstable plasma modes, as well as contribute to the validation of MHD codes. Analysis of the existing toroidal arrays on NSTX-U shows coverage of the torus is sufficient to simultaneously measure toroidal mode numbers up to n=3, but not to resolve the poloidal structure. The MHD code MARS-F/K has been used to identify poloidal locations that would improve the capability to measure stationary or near-stationary 3D fields that may result from the plasma response to external sources of non-axisymmetric fields. The study highlighted 6 poloidal positions where new arrays of both poloidal and radial magnetic field sensors will improve the poloidal resolution. Basing the sensor connection scheme on differences of pairs of probes and on the singular value decomposition condition number would allow a clear measurement of asymmetric signals. We propose configurations that would provide both a good signal/noise ratio and a good resilience of the array to the failure of a sensor. Supported by US DOE under grants DE-FC02-04ER54698, DE-FG02-99ER54522, DE-AC02-09CH11466.

Speakers: Stefano Munaretto (General Atomics), E.J. Strait (General Atomics), R.J. La Haye (General Atomics), M.J. Lanctot (General Atomics), C.E. Myers (Princeton Plasma Physics Laboratory), J.-K. Park (Princeton Plasma Physics Laboratory), Z. Wang (Princeton Plasma Physics Laboratory)
• 10:31
6.20 The upgraded JET Gamma-ray Camera based on high resolution/high count rate compact spectrometers 2h

The JET gamma ray camera has been very recently upgraded within the EUROFUSION enhancement program by the Gamma-ray Camera Upgrade (GCU) project. Aim of the GCU project is to improve the spectroscopic properties of the existing gamma ray camera both in terms of energy resolution and high counting rate capability, in order to operate in the forthcoming high power D and DT campaign. In this work we describe the solutions developed to meet the target requirements (Energy resolution <5% at 1.1 MeV and counting rate capability >500 kHz) which will enable high energy resolution/high count rate gamma-ray spectroscopy measurements in the 19 detectors of the horizontal and vertical camera. In particular, it was necessary to design, develop and realize a new compact gamma ray spectrometer based on a LaBr3 scintillator crystal (25.4 x 16.9 mm2) coupled to a Silicon Photo-Multiplier. The expected enhanced performance of the upgraded JET gamma ray camera will be presented with an example of the first D plasma data collected in the JET 2018 C38 campaign.

Speakers: Davide Rigamonti (Istituto di Fisica del Plasma “P. Caldirola”, CNR), Andrzej Broslawski (Narodowe Centrum Badań Jądrowych (NCBJ)), Ana Fernandes (Instituto de Plasmas e Fusão Nuclear, Instituto Superior Técnico, Universidade de Lisboa), Joao Figueiredo (EUROfusion Programme Management Unit, Culham Science Centre), Luca Giacomelli (Istituto di Fisica del Plasma “P. Caldirola”, CNR), Giuseppe Gorini (Dipartimento di Fisica “G. Occhialini”, Università degli Studi di Milano-Bicocca), Marcin Gosk (Narodowe Centrum Badań Jądrowych (NCBJ)), Garry Kaveney (Culham Centre for Fusion Energy), Vasili Kiptily (Culham Centre for Fusion Energy), Stefan Korolczuk (Narodowe Centrum Badań Jądrowych (NCBJ)), Andrea Murari (EUROfusion Programme Management Unit, Culham Science Centre), Massimo Nocente (Dipartimento di Fisica “G. Occhialini”, Università degli Studi di Milano-Bicocca), Rita Costa Pereira (Instituto de Plasmas e Fusão Nuclear, Instituto Superior Técnico, Universidade de Lisboa), Sergey Popovichev (Culham Centre for Fusion Energy), Arkadiusz Urban (Narodowe Centrum Badań Jądrowych (NCBJ)), Izabella Zychor (Narodowe Centrum Badań Jądrowych (NCBJ)), Marco Tardocchi (Istituto di Fisica del Plasma “P. Caldirola”, CNR), JET Contributors (Culham Centre for Fusion Energy)
• 10:31
6.21 Development of a New Reflectometry Endstation for Crystal Calibrations using Synchrotron Light Sources 2h

A new reflectometry endstation has been developed specifically for the utilization of synchrotron radiation–based light sources. This paper describes the experimental setup and associated capabilities designed to measure crystal diffractive properties for a wide range of crystals, cut orientations, and surface geometries, including flat, convex, concave, and imaging arrangements. We are now adapting the system to render it suitable for use on the new NNSA soft x-ray calibration beam line (SXR) located at Stanford Synchrotron Radiation Light Source. This beam line (16-2) is expected to come online later in 2018. The endstation setup is unique in that it also accommodates large reflection angles (>80°). The system has been prototyped and successfully commissioned at Lawrence Berkeley National Laboratory’s Advanced Light Source beam line 9.3.1. Data from various calibration studies of flat quartz (100) and potassium acid phthalate (KAP), cylindrically bent KAP ranging in radius of curvature from 2 to 9 inches, spherically bent quartz (203), 220Ge and 335Ge, and tronconique-bent CsAP (cesium biphthalate) are discussed. This work was done by MSTS, LLC, Contractor for the NNSS, under Contract DE-NA-0003624 and by SNL under contract DE-NA-0003525. DOE/NV/0003624--0025.

Speakers: Wayne Stolte (Nevada National Security Site), Ming Wu (Sandia National Laboratories), Franz Weber (Nevada National Security Site), Ken Moy (Nevada National Security Site), Chris Kruschwitz (Nevada National Security Site), Pat Lake (Sandia National Laboratories), Chris Bourdon (Sandia National Laboratories)
• 10:31
6.22 Study of the spatial localization of ECE measurement in LHW-heated plasmas 2h

Electron cyclotron emission (ECE) measurements have been a powerful tool in diagnosing the electron temperature profiles in magnetically confined plasmas. It has a fairly good spatial and temporal resolutions, and high sampling rate. However, the underlying physics is broken to some extent when the electron velocity distribution has a high energy tail. On EAST, LHW is of high priority because it is the most efficient current-driven technique and the system is very robust. Therefore, it is of great importance to quantitatively study the spatial localization of ECE measurements in LHW-heated plasmas. In this work, the EC emission layer is simulated by using the code SPECE. The results from this code for ohmic plasmas have been compared with an individual code developed at EAST, and the agreement is good. The results for the LHW-heated plasmas indicate that there are two emission layers for an individual frequency, and they are separately attributed to the thermal electrons and non-thermal electrons. Even though the non-thermal emission layer is very broad, the emission power is much smaller than that from the thermal emission layer. The preliminary results imply that the ECE data could be still useful as a localized measurement in LHW-heated plasmas.

Speakers: Yushu Zuo (Institute of Plasma Physics, Chinese Academy of Sciences), Yong Liu (Institute of Plasma Physics, Chinese Academy of Sciences), Tianfu Zhou (Institute of Plasma Physics, Chinese Academy of Sciences), Lorenzo Figini (Istituto di Fisica del Plasma, CNR), Ang Ti (Institute of Plasma Physics, Chinese Academy of Sciences), Hailin Zhao (Institute of Plasma Physics, Chinese Academy of Sciences), Bili Ling (Institute of Plasma Physics, Chinese Academy of Sciences)
• 10:31
6.23 Development of high speed full digital processing phase detector for interferometry 2h

A fully digital type phase detector for plasma interferometry is developing. It can operate even in the situation where the phase changes rapidly or where the input signal is too small to drive the correct phase change from the IF signal. It directly converts the IF signal waveform of the interferometer to the phase signal by a data processing in a logic circuit, thereby the phase is derived from the full waveform of the IF signal. The IF signal of the interferometer is converted to I/Q signals by Hilbert transform, processed with a digital low-pass filter, and polar coordinates are converted by a CORDIC algorithm to obtain the phase signal. A simulation of the high speed full digital processing phase detector shows that the fringe jump does not occur until a phase change rate of 0.85 × 10^6 rad/s. This value is sufficiently large as compared with the predicted phase velocity in density rise due to the pellet injection. The phase conversion has been simulated using the real IF signal of the interferometer measured with Heliotron J. The results show that the phase signal is successfully calculated by the full digital processing method from the IF signal in which the phase derivation is impossible by the conventional analog phase detector.

Speakers: Takashi Minami (Institute of Advanced Energy, Kyoto University), Yasuhiko Ito (National Institute for Fusion Science), Yoshiaki Ohtani (National Institutes for Quantum and Radiological Science and Technology), Shinsuke Ohshima (Institute of Advanced Energy, Kyoto University), Kazunobu Nagasaki (Institute of Advanced Energy, Kyoto University), Hideya Nakanishi (National Institute for Fusion Science), Ryo Yasuhara (National Institute for Fusion Science), Hisayoshi Funaba (National Institute for Fusion Science), Ichihiro Yamada (National Institute for Fusion Science), Tsuyoshi Akiyama (National Institute for Fusion Science)
• 10:31
6.24 Conceptual design for resistive bolometer system with multi-apertures for total radiation power measurement in JT-60SA 2h

In the previous study, design techniques with multiple apertures for a field of view (FoV) of the resistive bolometer system were developed [1] to reduce required number of bolometer channels for the determination of the total radiation power. In the present study, FoVs of the resistive bolometer system have been designed with previously developed techniques for JT-60SA. The FoV design is carried out with following setting requirements; (i) requirement of independent determination of the divertor and the main plasma radiation and (ii) limitation of a use of only allocated three diagnostic ports. The present design technique indicated that the main plasma can be covered with only two channels. The wide coverage by two channels is favorable for the replication of the bolometer system for improving reliability against the failure of a bolometer during experiment. It has been also confirmed that a radiation phantom placed at either of the main plasma region and the divertor region can be determined within 3 % and 15 % deviation, respectively, from the preset emissivity. In the conference, S/N ratio of the bolometer signal and estimated heat input on the bolometer with a simulated radiation profile will also be discussed. [1] R. Sano et.al., (to be submitted)

Speakers: Ryuichi Sano (National Institutes for Quantum and Radiological Science ad Technology), Masakatsu Fukumoto (National Institutes for Quantum and Radiological Science ad Technology), Tomohide Nakano (National Institutes for Quantum and Radiological Science ad Technology), Naoyuki Oyama (National Institutes for Quantum and Radiological Science ad Technology)
• 10:31
6.25 Validation of electron temperature profiles on W7-X as measured using a x-ray imaging crystal spectrometer 2h

A detailed description of the design and performance of the x-ray imaging crystal spectrometer systems (XICS, HR-XIS) installed on W7-X is presented, along with cross-validation of analysis methods and comparison with other diagnostic measurements. A detailed comparison of tomographically inverted electron temperature profiles from XICS is made with local measurements from Thomson scattering over a wide range of plasma parameters. These comparisons show good agreement within the range of electron temperatures that XICS is sensitive to, and highlight the use of XICS as a robust electron temperature profile diagnostic. Also presented is a comparison between measurements made using the four impurity spectra routinely recorded by the XICS system (Ar16+, Ar17+, Fe24+ and Mo32+). Finally a comparison of XICS analysis techniques between a Bayesian model using the Minerva framework, and a stepwise analysis based on fitting of line integrated spectra is shown.

Speakers: Novimir A. Pablant (Princeton Plasma Physics Laboratory), Andreas Langenberg (Max-Planck-Institut fur Plasmaphysik), Arturo Alonso (Laboratorio Nacional de Fusion, CIEMAT), Manfred Bitter (Princeton Plasma Physics Laboratory), Sergey Bozhenkov (Max-Planck-Institut fur Plasmaphysik), Rainer Burhenn (Max-Planck-Institut fur Plasmaphysik), Luis Delgado-Aparicio (Princeton Plasma Physics Laboratory), Golo Fuchert (Max-Planck-Institut fur Plasmaphysik), David Gates (Princeton Plasma Physics Laboratory), Ken W. Hill (Princeton Plasma Physics Laboratory), Udo Hoefel (Max-Planck-Institut fur Plasmaphysik), Matthias Hirsch (Max-Planck-Institut fur Plasmaphysik), James Kring (Auburn University), Oleksandr Marchuk (Institut fur Energie und Klimaforschung, Plasmaphysik, Forschungszentrum Julich), Michael Mardenfeld (Princeton Plasma Physics Laboratory), Ekkehard Pasch (Max-Planck-Institut fur Plasmaphysik), Andrea Pavone (Max-Planck-Institut fur Plasmaphysik), Matthew Reinke (Oak Ridge National Laboratory), Evan Scott (Max-Planck-Institut fur Plasmaphysik), Jakob Svennson (Max-Planck-Institut fur Plasmaphysik), Peter Traverso (Auburn University), Gavin Weir (Max-Planck-Institut fur Plasmaphysik), Thomas Wegner (Max-Planck-Institut fur Plasmaphysik), the W7-X Team (Max-Planck-Institut fur Plasmaphysik)
• 10:31
6.26 Development of an Ultra-Fast Photomultiplier Tube for the Next Generation Of Gamma-Ray Cherenkov Detectors for The National Ignition Facility 2h

A new ultra-fast photomultiplier tube with associated drivers has been developed for use in the next generation of Gamma-ray Cherenkov detectors for the National Ignition Facility (NIF). Pulse-dilation technology has been applied to a modified standard MCP based photomultiplier tube (PMT) to improve the temporal response time by about 10X. The new tube has been packaged suitably for deployment on the NIF and remote electronics designed to deliver the required non linear waveforms to the pulse dilation electrode. This is achieved with an avalanche pulse generator system capable of generating fast waveforms, arbitrarily over the useful parameter space. The pulse is delivered via impedance matching transformers and isolators, allowing the cathode to be ramped very quickly between two high voltages in a controlled non-linear manner. This results in near linear pulse dilation over several ns. The device has a built in fiducial system that allows easy calibration and testing with FO laser sources. Results will be presented demonstrating the greatly improved response time and other parameters of the device.

Speakers: Anthony Dymoke-Bradshaw (Kentech Instruments Ltd.), Jonathan Hares (Kentech Instruments Ltd.), James Milnes (Photek)
• 10:31
6.27 Testing a Cherenkov Neutron Time-of-Flight Detector on OMEGA 2h

A Cherenkov neutron time-of-flight (nTOF) detector developed and constructed at LLNL was tested on OMEGA 13 m from the target in a collimated line of sight and at 5.3 m from the target in the open space inside the OMEGA Target Bay. The neutrons interacting with the quartz rod generate gammas, which, through Compton scattering, produce relativistic electrons that give rise to Cherenkov light. The Cherenkov nTOF detector consists of 8-mm-diam, 25-cm quartz hexagonal prism coupled with Hamamatsu gated microchannel plate photomultiplier tube R5916U-52. The tests were performed in DT direct-drive implosions with cryogenic and room-temperature targets with a wide range of neutron yields and ion temperatures. The results of the tests and comparison with other nTOF detectors on OMEGA will be presented. This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0001944.

Speakers: Vladimir Glebov (Laboratory for Laser Energetics, University of Rochester), Mark Joseph Eckart (LLNL), Chad Forrest (LLE), Gary Patrick Grim (LLNL), Edward Hartouni (LLNL), Robert Hatarik (LLNL), James Knauer (LLE), Alastair Moore (LLNL), Sean Regan (LLE), Thomas Craig Sangster (LLE), David Schlossberg (LLNL), Christian Stoeckl (LLE)
• 10:31
6.28 Development of a HELIOS Diagnostic using a Fast Piezoelectric Valve for the Prototype Material Plasma Exposure eXperiment 2h

A new helium line-ratio spectral monitoring (HELIOS) diagnostic, using a piezoelectric valve with high duty cycles (on/off times ≲0.5 ms), allowing for good background correction, and measured particle flowrates on the order of ~1020 particles/second is being implemented on Oak Ridge National Laboratory’s (ORNL) Prototype Material Plasma Exposure eXperiment (Proto-MPEX). The HELIOS diagnostic is constructed so that the nozzle sits as close to the plasma column as possible, injecting helium directly into the plasma during operations. Fiber optics transfer the light emission from the plasma at the time of the helium puff(s) to a Filterscope system where intensity is measured at 100 kHz for three separate helium lines: 667.9 nm, 706.53 nm, and 728.0 nm. The open magnetic geometry of Proto-MPEX is ideal for testing and characterizing a HELIOS diagnostic system, comparing the derived ne and Te values to nearby double Langmuir probes and Thomson scattering measurements. Preliminary results imply a temperature and density range of 30-5 eV and 1x10^19 m-3 – 1x10^20 m-3, respectively, in the helicon region of Proto-MPEX. This work was supported by the US. D.O.E. contract DE-AC05-00OR22725 and DE-SC00013911.

Speakers: Holly Ray (Oak Ridge National Laboratory), Theodore Biewer (Oak Ridge National Laboratory), Juan Caneses (Oak Ridge National Laboratory), Jonathan Green (University of Wisconsin-Madison), Levon McQuown (University of Wisconsin-Madison), Oliver Schmitz (University of Wisconsin-Madison)
• 10:31
6.29 Thomson scattering systems on C-2W field-reversed configuration plasma experiment 2h

TAE Technologies’ newly constructed C-2W experiment aims to improve the ion and electron temperature (Te) in a sustained field-reversed-configuration (FRC) plasma. A suite of Thomson scattering systems has been designed and constructed for electron temperature and density (ne) profile measurement. The systems are designed for electron density and temperature ranges of 1×10(12) cm(-3) to 2×10(14) cm(-3) and 10eV to 2keV. The central system will provide profile measurement of Te/ne at 16 radial locations from r = -9cm to r = 64cm with a temporal resolution of 20kHz/4 pulses or 1kHz/30 pulses. The jet system will provide profile measurement of Te/ne at 5 radial locations in the open field region from r = -5cm to r = 15cm with a temporal resolution of 100Hz. The systems and their components have been characterized and calibrated [1,2]. A maximum-likelihood algorithm has been applied for data processing and analysis. [1] T. Schindler Calibrations of Thomson Scattering Diagnostic on C-2W HTPD 2018 [2] A. Ottaviano Characterization of System Components for Thomson Scattering Diagnostics on C-2W HTPD 2018

Speakers: Kan Zhai (TAE Technologies, Inc.), Tania Schindler (TAE Technologies, Inc.), Angelica Ottaviano (TAE Technologies, Inc.), Helen Zhang (TAE Technologies, Inc.), Dan Fallah (TAE Technologies, Inc.), Jason Wells (TAE Technologies, Inc.), Matthew Thompson (TAE Technologies, Inc.), the TAE Team (TAE Technologies, Inc.)
• 10:31
6.30 The LLNL warm electron beam ion trap (WEBIT): An instrument for calibrating space-borne X-ray spectrometers 2h

The warm electron beam ion trap (WEBIT) is being developed as a calibration source for space-borne, high-throughput, high-resolution X-ray spectrometers, such as the X-ray Astrophysics Recovery Mission (XARM) Resolve quantum calorimeter. Historically, calibration sources for calorimeter spectrometers have relied on characteristic line emission from x-ray tubes, fluorescing metals, and radioactive sources. The WEBIT, in contrast, relies on emission from x-ray transitions in hydrogenic and helium-like ions whose energies are well known and whose line shapes are relatively simple. The WEBIT can create astrophyscially relevant ions whose x-ray emission falls in the 0.3 to 12 keV science bandpass of Resolve and has a portable design advantageous for a calibration source. The WEBIT will be used to calibrate Resolve’s instrumental line shape and gain scale as a function of various operational parameters during both detector subsystem level and instrumental level testing. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

Speakers: T.E. Lockard (Lawrence Livermore National Laboratory), E.W. Magee (Lawrence Livermore National Laboratory), G.V. Brown (Lawrence Livermore National Laboratory), N. Hell (Lawrence Livermore National Laboratory), M.A. Leutenegger (Goddard Space Flight Center-NASA), M. E. Eckart (Goddard Space Flight Center-NASA), P. Beiersdorfer (Lawrence Livermore National Laboratory)
• 10:31
6.31 Millimeter-Wave Far-Forward Scattering for Density Fluctuation Measurements on LTX-β 2h

The λ≈1 mm (f=288 GHz) interferometer for the Lithium Tokamak Experiment β (LTX-β) device will use a centerstack-mounted retro-reflector mirror to provide line density measurements along a single radial chord at the midplane. Previously this diagnostic has been used for routine line density measurements in LTX. The current work investigates the capabilities of the system as a simultaneous far-forward scattering diagnostic, which can provide line-integrated measurement of density fluctuations within the divergence of the probe beam for perpendicular wavenumbers k⟂≲2 cm^-1. The far-forward scattering diagnostic is expected to provide enhanced sensitivity for high frequency coherent density oscillations (e.g. Alfvénic modes due to NBI on LTX-β) as well as for broadband turbulence. Comprehensive simulations of the scattered beam using beam tracing and full-wave codes will be used to develop quantitative estimates for the scattered signal using target fluctuations. These calculations will also consider the 3-D scattering geometry due to the magnetic configuration of the spherical tokamak and the radial view of the diagnostic. Analysis of data from previous measurements on LTX will also be presented. Supported by U.S. DoE Contracts DE-FG02-99ER54527 and DE-AC02-09CH11466.

Speakers: Shigeyuki Kubota (UCLA), R. Majeski (PPPL), D.P. Boyle (PPPL), R. Kaita (PPPL), T. Kozub (PPPL), E. Merino (PPPL), X.V. Nguyen (UCLA), W.A. Peebles (UCLA), T.L. Rhodes (UCLA)
• 10:31
6.32 Pixel-to-pixel variation on a calibrated PILATUS3-based multi-energy soft x-ray detector 2h

A multi-energy soft X-ray pin-hole camera based on the PILATUS3 100K x-ray detector, produced commercially by Dectris Ltd., has recently been installed on the Madison Symmetric Torus. This photon-counting detector consists of a two-dimensional array of ~100,000 pixels for which the photon lower-threshold cutoff energy ¬Ec can be independently set for each pixel, allowing the measurement of plasma x-ray emissivity in multiple energy ranges with a unique combination of spatial and spectral resolution and the inference of a variety of important plasma properties (e.g. Te, nZ, Zeff). The energy dependence of each pixel is calibrated for the 2-7 keV range by scanning individual “trimbit” settings, which set Ec, while the detector is exposed to fluorescence emission from Ag, In, Mo, Ti, V, and Zr targets. The resulting data for each line are then fit to a characteristic “S-curve” which determines the mapping between the 64 possible trimbit settings and Ec for each pixel. The statistical variation of this calibration from pixel-to-pixel and its effect on overall energy resolution are explored. This material is based upon work supported by the U.S. Department of Energy Office of Science, Office of Fusion Energy Sciences program under Award Numbers DE-SC0015474 and DE-FC02-05ER54814.

Speakers: Patrick VanMeter (Department of Physics, University of Wisconsin-Madison), Luis Felipe Delgado-Aparicio (Princeton Plasma Physics Laboratory (PPPL)), Lisa Reusch (University of Wisconsin-Madison), Novimir Pablant (Princeton Plasma Physics Laboratory (PPPL)), Jake Maddox (Department of Engineering Physics, University of Wisconsin-Madison), Michael Rissi (DECTRIS Ltd.), Benjamin Luethi (DECTRIS Ltd.), Kenneth Hill (Princeton Plasma Physics Laboratory (PPPL)), Daniel Den Hartog (Department of Physics, University of Wisconsin-Madison)
• 10:31
6.33 Accuracy of Assuming a Maxwellian Electron Distribution Function in ThomsonScattering Analysis of Non-Maxwellian Plasmas 2h

Collective Thomson scattering provides precise density and temperature measurements in many plasma-physics experiments. The accuracy of these measurements is dependent on the underlying assumptions in deriving the structure factor S(k,ω). The core assumption made is that the underlying electron distribution functions in inertial confinement fusion relevant plasmas are Maxwellian. Here we present a statistically based, quantitative analysis of the uncertainties, from these assumptions, in the measured electron density and temperature. This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0001944.

Speaker: Avram Milder (University of Rochester - Laboratory for Laser Energetics)
• 10:31
6.34 A Platform for X-Ray Thomson Scattering Measurements of Radiation Hydrodynamics Experiments on the NIF 2h

A recent experiment on the National Ignition Facility(NIF) radiographed the evolution of the Rayleigh-Taylor(RT) instability under high and low drive cases, where high drive means the radiation energy flux is comparable to the mass energy flux. This experiment showed that under a high drive the growth rate of the RT instability is reduced relative to the low drive case. It is believed the high drive launches a radiative shock, increases the temperature of the post-shock region, and ablates the spikes, which reduces the RT growth rate. The plasma parameters must be measured to validate this claim. We present a target platform for making X-Ray Thomson Scattering(XRTS) measurements on radiation hydrodynamics experiments on NIF to measure the electron temperature of the shocked region in the above cases. We show that a previously fielded NIF radiation hydrodynamics platform can be modified to allow for non-collective XRTS measurements. Photometrics and a noise estimation using synthetic scattering spectra are performed to demonstrate the measurement error. This work is funded by the NNSA-DS and SC-OFES Joint Program in High-Energy-Density Laboratory Plasmas, grant number DE-NA0002956 and the National Science Foundation through the Basic Plasma Science and Engineering program.

Speakers: Heath LeFevre (University of Michigan Climate and Space Sciences and Engineering), Kevin Ma (University of Michigan Climate and Space Sciences and Engineering), Pat Belancourt (University of Michigan Climate and Space Sciences Engineering), Michael MacDonald (University of California Berkeley), Tilo Doeppner (Lawrence Livermore National Laboratory), Paul Keiter (University of Michigan Climate and Space Sciences and Engineering), Carolyn Kuranz (University of Michigan Climate and Space Sciences and Engineering)
• 10:31
6.35 Qualification of implanted depth markers for erosion and deposition studies in fusion experiments 2h

A novel method for measuring erosion of high-Z plasma facing components (PFCs) has been developed using bulk materials implanted with a single isotope a few microns deep or shallower from the surface. Changes to the depth of the implanted isotope, measured by particle-induced gamma emission, indicate erosion/deposition at the surface of the PFC. In addition to applicability in ex situ analysis, implanted depth markers can be deployed for an Accelerator-based In situ Materials Surveillance (AIMS) diagnostic, which enables shot-by-shot analysis of the inner wall in fusion energy experiments. This work describes the characterization of the implanted layer, as well as assessment of its viability in terms of thermal stability and the retention of bulk properties of the PFC surface layer traversed by the implanting beam. Implantation temperatures from 300 to 700 C and sample baking from 120 to 1000 C for 1 to 24 hours were studied. A synthetic diagnostic developed to assess measurement sensitivity and aid in interpreting experimental data shows excellent agreement between simulated and experimental measurements. The experiments, combined with the synthetic diagnostic, show erosion/deposition sensitivities of ~ 40 nm for high-Z PFCs.

Speakers: Leigh Ann Kesler (MIT Plasma Science and Fusion Center), Zach Hartwig (MIT Plasma Science and Fusion Center), Rajesh Maingi (Princeton Plasma Physics Laboratory), Dennis Whyte (MIT Plasma Science and Fusion Center), Graham Wright (MIT Plasma Science and Fusion Center), Kevin Woller (MIT Plasma Science and Fusion Center)
• 10:31
6.36 Developing a bright high-energy continuum backlighter for EXAFS on NIF 2h

Extended X-ray Absorption Fine Structure (EXAFS) spectroscopy is a powerful tool for in situ characterization of matter in the high energy density regime. An EXAFS platform is currently being developed on the National Ignition Facility (NIF). Development of a suitable X-ray backlighter involves minimizing the temporal duration and source size while maximizing spectral smoothness and brightness. One approach involves imploding a spherical shell, which generates a large of amount of heat and an X-ray flash near stagnation. Radiation hydrodynamics modeling improvements for EXAFS are possible by filling the shell with a moderate-Z gas. Here we present measurements of X-ray source size, spectral-temporal emission, and integrated spectrum produced by imploded Ar-filled CH shells. Compared to an unfilled shell, we find that 1 atm Ar fill significantly increases the X-ray yield but also increases the source size, whereas 4 atm Ar fill produces a similar yield but reduced the source size. This work performed under the auspices of the Lawrence Livermore National Security, LLC, (LLNS) under Contract No. DE-AC52-07NA27344.

Speakers: Andrew Krygier (Lawrence Livermore National Laboratory), Federica Coppari (Lawrence Livermore National Laboratory), Gregory Elijah Kemp (Lawrence Livermore National Laboratory), Daniel Thorn (Lawrence Livermore National Laboratory), Jon Eggert (Lawrence Livermore National Laboratory), Hye-Sook Park (Lawrence Livermore National Laboratory), Yuan Ping (Lawrence Livermore National Laboratory), Bruce Remington (Lawrence Livermore National Laboratory), Marilyn Schneider (Lawrence Livermore National Laboratory)
• 10:31
6.37 First result of dispersion interferometer based on CO2 laser on EAST 2h

Dispersion interferometer (DI) can avoid the influence of mechanical vibration, and without the fringe jump error at the highest line-integrated electron density (1020m-2) on Experimental Advanced Superconducting Tokamak (EAST). In previous bench test, the power distribution curve with nonlinear crystal angle rotation of second harmonic laser has been verified, the line-integrated density can be measured with 1017m-2 sensitivity and 20 μs temporal resolution. In this paper, a dispersion interferometer based on a CO2 laser with dual plasma passage measurements of line-integrated electron density on EAST has been built and will be tested in experiments. The DI system did not need vibration isolator, most components are installed on two floors bench which welding in a stable laser room with vibration less than 10 μm, the CO2 laser beam vertical through the vacuum vessel and 9cm from the center of the plasma. The whole system has been built and prepare for the experiment on EAST. The development of multi-channel dispersion interferometer is discussed.

Speakers: Weiming Li (ASIPP, CAS), Haiqing Liu (ASIPP, CAS), Yao Yang (ASIPP, CAS), Long Zeng (ASIPP, CAS), Yuan Yao (ASIPP, CAS), Zhiyong Zou (ASIPP, CAS), Xuechao Wei (ASIPP, CAS), Yinxian Jie (ASIPP, CAS)
• 10:31
6.38 Characterization of Selenium Heα x-ray source on the National Ignition Facility 2h

There are many high-energy-density experiments that require efficient atomic line emission x-ray sources for diagnostic applications such as imaging (e.g. backlit radiography) and material testing (e.g. diffraction measurements). To date, most well-characterized laser-generated line sources efficient enough for these purposes have photon energies ≤10.2 keV. They are typically created by irradiating a thin foil using a 351nm, long pulse laser (≥1 ns) in the range of 1015 W/cm2. The dominant line emission, Heα, from these sources is the result of 2p –> 1s transitions from He-like ions. For the new Crystal Backlighter Imager at the National Ignition Facility (NIF), we developed a Selenium Heα source at 11.652 keV. The Se He-like line emission was investigated in terms of absolute spectra and laser conversion efficiency into the lines as a function of viewing angle relative to the foil normal. Time-integrated and time-resolved data from multiple NIF shots will be presented. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344 and by General Atomics under Contract DE-NA0001808.

Speakers: Christine Krauland (General Atomics), Maria A. Barrios (Lawrence Livermore National Laboratory), Daniel B. Thorn (Lawrence Livermore National Laboratory), Marilyn B. Schneider (Lawrence Livermore National Laboratory), Gareth N. Hall (Lawrence Livermore National Laboratory), Otto L. Landen (Lawrence Livermore National Laboratory)
• 10:31
6.39 The particle time-of-flight (pTOF) detector for high-yield (>1016) implosions at the National Ignition Facility 2h

The particle time-of-flight (pTOF) detector is a polycrystalline CVD-diamond photoconducting diode, which has been used to measure the shock-and compression- bang time using fusion products from DD, D3He or DT reactions in Inertial Confinement Fusion implosions at the National Ignition Facility (NIF). Current implementations of the pTOF detector have been able to provide these measurements for nuclear yields in the range of 1010-1015. However, numerous NIF implosions have generated yields which exceed the sensitivity range of pTOF. A bang time measurement for a NIF implosion with a yield of 5×1016 using a 1 cm diameter pTOF detector requires a maximum sensitivity of 5×10-11 V ns per DT neutron. In this contribution, we present the path for implementing a low-sensitivity pTOF detector for bang-time measurements in high-yield (~1016) implosions using a single crystalline diamond. Data presented from recent OMEGA implosions will test if single crystal diamond detectors can achieve the desired sensitivity thresholds for NIF. Having bang time measurements will be essential in our effort of understanding the timing difference between x-ray and nuclear bang-times in ICF implosions. This work was supported in part by DOE and LLNL (Subcontract No. B613027).

Speakers: P. J. Adrian (MIT), N. Kabadi (MIT), H. Sio (MIT), M. Johanson (MIT), J. Frenje (MIT), B. Lahmann (MIT), R. Simpson (MIT), R. Petrasso (MIT), J. Knauer (LLE), V. Glebov (LLE)
• 10:31
6.40 An Ion Beam System for Absolute Calibration of Neutral Particle Detectors for C-2W 2h

A high-confinement operating regime with plasma lifetimes significantly exceeding previous empirical scaling laws was recently obtained by combining plasma gun edge biasing and Neutral Beam Injection in the C-2U field-reversed configuration (FRC) experiment [1]. Several diagnostics used on the C-2U device to measure fast neutral flux have been relatively calibrated, including neutral particle analyzers [2] (NPA) and neutral particle bolometers [3] (NPB). However, absolute calibration is required to take full advantage of these instruments' capabilities for the C-2W experiment. A Calibration Ion Beam (CIB) system has been constructed for this purpose and here we present performance characteristics of this device as well as calibration results for neutral particle detectors. [1] M. W. Binderbauer, et al., Physics of Plasmas 22, 056110 (2015). [2] R. Clary, et al., Review of Scienti

Speakers: Ryan Clary (TAE Technologies, Inc.), Alan Perstin (TAE Technologies, Inc.), Sergey Korepanov (TAE Technologies, Inc.), Anton Kolmogorov (Budker Institute of Nuclear Physics), Vladimir Davydenko (Budker Institute of Nuclear Physics), Alexander Ivanov (Budker Institute of Nuclear Physics), Grigory Shulzhenko (Budker Institute of Nuclear Physics), the TAE Team (TAE Technologies, Inc.)
• 10:31
6.41 Using multiple nToF detectors to determine hot spot velocity 2h

An important diagnostic value of a shot at the National Ignition Facility (NIF) is the resultant center-of-mass motion of the imploding capsule. This residual velocity contributes to the efficiency of converting LASER energy into plasma temperature. A new analysis method extracts the effective hot spot motion by using information from multiple nToF lines-of-sight (LoS). This technique fits a near Gaussian spectrum to the nToF scope traces and overcomes reliance on models to relate the plasma temperature to the mean energy of the emitted neutrons and requires to have at least four nToF LoS. Results analyzing DT as well DD peaks on recent NIF shots with this technique will be presented. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

Speakers: Robert Hatarik (LLNL), Ryan C. Nora (LLNL), Brian K. Spears (LLNL), Mark J. Eckart (LLNL), Gary P. Grim (LLNL), Edward P. Hartouni (LLNL), Alastair S. Moore (LLNL), David J. Schlossberg (LLNL)
• 10:31
6.42 Experimental considerations to observe two ionizing fronts in systems with a sharp absorption edge 2h

The interaction of radiation with media is a ubiquitous phenomenon. In astrophysics, ionizing radiation interacts with molecular clouds with the fate of the clouds determined by the optical depth of the cloud. In inertial confinement fusion (ICF) radiation interacts with the capsule, ablating material and driving shocks. Recent work by Poujade et al (2015) performed simulations, which indicate that if the opacity of the medium has a sharp edge in the radiation spectral domain a second ionization front can form. This second ionization front can form a second shock, which they termed an edge-shock. One example they consider is radiation from a 100 eV source incident on carbon. In this case, the carbon K-edge (~282 eV) corresponds to the peak of the radiation and the simulation shows the source radiation is deposited at two different locations creating both the main shock and an edge shock. IN ICF simulations, extra shocks are often observed and may be due to this mechanism. We will discuss the experimental considerations to observe both the main and edge shock in such a system. We will also present a preliminary experimental design.

Speakers: Paul Keiter (University of Michigan), Robert VanDervort (University of Michigan), Matt Thrantham (University of Michigan), R. Paul Drake (University of Michigan)
• 10:31
6.43 Jet Outflow and Open Field Line Measurements on the C-2W Advanced Beam-Driven Field-Reversed Configuration Plasma Experiment 2h

Accurate operation and high performance of the open field line plasma surrounding the Field Reversed Configuration (FRC) is crucial to achieving the goals of successful temperature ramp up and confinement improvement on C-2W. Knowledge and control of the open field line plasma requires extensive diagnostic efforts. A suite of diagnostics, which consists of microwave interferometry, dispersive spectroscopy and spatial heterodyne spectroscopy, is being developed to measure electron density, ion temperature and particle outflow velocity at various locations along the open magnetic field lines. A detailed overview of these diagnostics is presented.

Speakers: Daniel Sheftman (TAE Technologies, Inc.), Roger Smith (TAE Technologies, Inc.), Lothar Schmitz (TAE Technologies, Inc.), Deepak Gupta (TAE Technologies, Inc.), Matthew Thompson (TAE Technologies, Inc.)
• 10:31
6.44 Laser and pulsed power x-ray backlighters for electron density imaging using a Talbot-Lau x-ray deflectometer 2h

A Talbot-Lau X-ray interferometer can map electron density gradients in High Energy Density (HED) samples. In the x-ray deflectometry configuration a single Moiré image can provide refraction, attenuation, elemental composition, and scatter information. In order to make the diagnostic available for a wide range of HED experiments, pulsed power and high power laser produced x-ray sources were evaluated as potential backlighters for an 8 keV Talbot-Lau x-ray deflectometer consisting of free standing ultrathin gratings. For pulsed power experiments, single (2 × 64 μm) and double (4 × 25 μm) copper x-pinches were driven at ∼1 kA/ns. For high power laser experiments, K-alpha emission was obtained by illuminating copper targets (500 x 500 x 12.5 µm3 foils, 20 µm diameter wire, and >10 µm diameter spheres) with a 30 J, 8-30 ps laser pulse and a 25 um Cu wire with a 60 J, 10 ps laser pulse. Grating survival was assessed along with fringe formation and contrast for all x-ray sources. Electron density profiles were obtained while the diagnostic and detector performance (x-ray film, CCD, and imaging plates) was analyzed in context of high energy density sample characterization. The results demonstrate the potential of TXD as an electron density diagnostic for HED plasmas.

Speakers: Maria Pia Valdivia (Johns Hopkins University), F. Veloso (Pontificia Universidad Católica de Chile), D. Stutman (Johns Hopkins University), C. Stoeckl (Laboratory for Laser Energetics), C. Mileham (Laboratory for Laser Energetics), I. A. Begishev (Laboratory for Laser Energetics), W. Theobald (Laboratory for Laser Energetics), S. R. Klein (Center for Laser Experimental Astrophysical Research), M. Vescovi (Pontificia Universidad Católica de Chile), G. Muñoz-Cordovez (Pontificia Universidad Católica de Chile), V. Valenzuela-Villaseca (Pontificia Universidad Católica de Chile), A. Casner (Université de Bordeaux-CNRS-CEA), M. Koenig (LULI, Ecole Polytechnique), B. Albertazzi (LULI, Ecole Polytechnique), P. Mabey (LULI, Ecole Polytechnique), T. Michel (LULI, Ecole Polytechnique), G. Rigon (LULI, Ecole Polytechnique), S. Pikuz (Joint Institute for High Temperatures, Russian Academy of Sciences), J. Bromage (Laboratory for Laser Energetics), S.P. Regan (Laboratory for Laser Energetics)
• 10:31
6.45 Application of a hall sensor to pulse magnetic field measurement in the FAT-CM FRC experiments 2h

Collisional merging experiments of a field-reversed configuration (FRC) at super-Alfvénic velocity have been conducted in the FAT-CM device. In the experiments, two FRCs accelerated to the velocity of 150 – 200 km/s are collided and merged in the confinement section with a quasi-static confinement magnetic field. Therefore, it is necessary to measure high-frequency pulse magnetic field superposed on a quasi-stationary signal. The magnetic field is generally measured by a magnetic coil in the pulse discharge experiments, however the coil has nonlinear characteristics in the wide frequency of the conducted experiments. Therefore, a hall sensor has been applied as a wideband magnetic field measurement in the FAT-CM experiments. On a magnetic field measurement in the confinement section, it is confirmed that the sensor has the response speed and linear characteristic for the magnetic field with the rising time of about 40 ms and its output voltage does not saturate in the magnetic field of about 0.09 T. Combination of the hall sensor and the magnetic coil realizes complete measurements of the magnetic field in the range of the FAT-CM experiments. In this work, dynamic process of collisional merging in the FAT-CM has been measured by the combined magnetic diagnostic system.

Speakers: Akiyoshi Hosozawa (Nihon University), Junichi Sekiguchi (Nihon University), Tomohiko Asai (Nihon University), Tsutomu Takahashi (Nihon University)
• 10:31
6.46 Results of commissioning experiments using the NIF Optical Thomson Scattering VUV Spectrometer 2h

A time-resolved, vacuum-ultra-violet (VUV) spectrometer diagnostic has been implemented on the National Ignition Facility (NIF). This spectrometer is designed to make Optical Thomson Scattering (OTS) measurements of the key plasma parameters in under-dense Inertial Confinement Fusion Hohlraum plasmas. We present the results of the initial commissioning experiments which were carried out in 2016/2017. These experiments include 3ω (351nm) Thomson scattering measurements of the plasma parameters of plasma plumes launched via laser-heating a plastic disc, and background VUV emission measurements in ICF relevant hohlraum target configurations. We will discuss the results, as well as ongoing work to improve the diagnostic performance in preparation for commissioning of the forthcoming 5ω (211nm) OTS probe laser, which is scheduled for commissioning in late 2018.

Speakers: George Swadling (Lawrence Livermore National Lab), James Steven Ross (Lawrence Livermore National Laboratory), Philip Datte (Lawrence Livermore National Laboratory), Justin Galbraith (Lawrence Livermore National Laboratory), Anastasia Manuel (Lawrence Livermore National Laboratory), Gene Freiders (Lawrence Livermore National Laboratory), Gene Vergel De Dios (Lawrence Livermore National Laboratory), John Moody (Lawrence Livermore National Laboratory)
• 10:31
6.47 Radially Scanning Magnetic Probes to Study Local Helicity Injection Dynamics 2h

To study Local Helicity Injection (LHI) dynamics and current drive, a new insertable B ̇ magnetic probe was deployed on the Pegasus spherical tokamak. The Magnetic Radial Array (MrA) probe consists of an array of 15 pickup coils (~5×8 mm each) that measure B ̇_z(R) over a 15 cm linear extent. The coils consist of traces embedded in a printed circuit board (PCB), with twisted-pair wires bringing the signal off the PCB to reduce noise. Three different coil designs are utilized to balance frequency response and coil sensitivity. Helmholtz coil measurements confirm bandwidth of ≲3.5 MHz and sensitives of 0.18/0.35/0.96 mV T^(-1) s. The probe uses the carbon armor and vacuum assembly from an existing probe. MrA probe measurements during LHI show significant magnetic activity at ~600 kHz that is localized to the plasma edge. To complement this high-speed B ̇ array, a lower-bandwidth (≤40 kHz) B(R) probe array is being developed. It utilizes ratiometric Hall effect sensors (with built-in amplifiers and compensators) that are mounted in a 3D printed form. This probe will provide measurements of field strength (|B|≤120 mT) and direction at 10 spatial points (ΔR=1.5 cm), to support studies of equilibrium field structure and current dynamics. Work supported by US DOE grant DE-FG02-96ER54375

• 10:31
6.48 Internal Magnetic Field Measurements of Translated and Merged Field-Reversed Configuration Plasmas in the FAT-CM Device 2h

Field-reversed configuration (FRC) Amplification via Translation – Collisional Merging (FAT-CM) experiments have recently commenced to study physics phenomena of collisions and merged FRC plasma states [1]. Two independently formed FRCs are translated into the confinement region of the FAT-CM device, collided near the midplane of the device with a relative speed of up to ~400 km/s, and a final merged FRC plasma state is achieved; this FRC collisional merging technique is essentially the same as in the C-2/C-2U experiments [2,3]. To measure magnetic field profiles of the translated and merged FRC plasmas, an internal magnetic probe array, developed/provided by TAE Technologies [3], has been installed in the midplane of the FAT-CM device. Initial magnetic field measurements indicate that both the translated and the merged FRC plasma states exhibit a clear field-reversal structure, which is qualitatively in good agreement with 2-D MHD simulations.
[1] F. Tanaka et al., in 26th Int’l Toki Conf., P2-17 (2017).
[2] M.W. Binderbauer et al., Phys. Rev. Lett. 105, 045003 (2010).
[3] H. Gota et al., Rev. Sci. Instrum. 83, 10D706 (2012).

Speakers: Hiroshi Gota (TAE Technologies, Inc.), Junpei Ishiwata (Nihon University), Fumiyuki Tanaka (Nihon University), Akiyoshi Hosozawa (Nihon University), Tomohiko Asai (Nihon University), Tsutomu Takahashi (Nihon University), Junichi Sekiguchi (Nihon University), Thomas Roche (TAE Technologies, Inc.), Sean Dettrick (TAE Technologies, Inc.), Yung Mok (TAE Technologies, Inc.), Michl Binderbauer (TAE Technologies, Inc.), Toshiki Tajima (University of California, Irvine)
• 10:31
6.49 Real-time phase calibration of the DIII-D density profile reflectometer system 2h

Real-time phase calibration of the ITER profile reflectometer is essential due to the long plasma duration and path length changes during a discharge. Progress has been recently made in addressing this issue by employing real-time phase calibration on the DIII-D profile reflectometer system. With installing a thin wire perpendicularly at the end of the waveguide transmission system, the round trip phase shift from the wire is detected simultaneously with the plasma phase shifts. Variations in the reflectometer round trip path length (~26 m) can then be determined during each DIII-D plasma discharge, allowing the variation in the phase due to this movement to be accounted for and removed. The round-trip reflectometer path length is observed to vary by ~3 mm (RMS value) during a DIII-D discharge. With the real-time correction, the measurement accuracy is improved. Since the wire retro-reflected signal is ~10 dB smaller than the plasma signal, no effect is observed on the plasma density measurement. Importantly, the wire calibration signal is approximately independent of the reflectometer launch polarization, allowing this polarization to be changed to match the plasma pitch angle. Supported by the U.S. DOE under DE-FG02-08ER54984 and DE-FC02-04ER54698.

Speakers: L Zeng (University of California, Los Angeles), G Wang (UCLA), T.L. Rhodes (UCLA), W.A. Peebles (UCLA), C Sung (UCLA)
• 10:31
6.50 A space-resolved extreme ultraviolet spectrometer for radial profile measurement of tungsten ions in the EAST tokamak 2h

EAST tokamak has been equipped with upper tungsten divertor since 2014 to improve the heat exhaust capability. In order to study the behavior and radial transport of tungsten ions in long-pulse H-mode plasmas, a space-resolved spectrometer working at 30-570Å is newly developed to measure the tungsten emission profile. Good spectral resolution of Δλ0 = 4-5 pixels, sufficient temporal resolution up to 50ms/frame and high spatial resolution of 0.8cm are obtained simultaneously. Absolute intensity calibration is carried out by comparing the bremsstrahlung continuum intensity between EUV and visible ranges. Radial profiles of tungsten emissions from 4p-4s and 4p-4p transitions in W42+ – W45+ ions are successfully obtained at 45-70 Å and 120-140 Å in high-temperature discharges (Te>2.5keV), e.g. W43+ at 61.334Å, W44+ at 60.93Å, W45+ at 62.336 Å, W42+ at 129.41Å, W43+ at 126.29 Å and W45+ at 126.998Å. Radial density profiles of W42+ – W45+ ions are analyzed with measured Te and ne profiles and photon emissivity coefficient (PEC) from ADAS database.

Speakers: Ling ZHANG (Institute of Plasma Physics, Chinese Academy of Sciences), Shigeru MORITA (National Institute for Fusion Science), Zong XU (Institute of Plasma Physics, Chinese Academy of Sciences), Xiuda YANG (Institute of Plasma Physics, Chinese Academy of Sciences), Pengfei ZHANG (Institute of Plasma Physics, Chinese Academy of Sciences), Yingjie CHEN (Institute of Plasma Physics, Chinese Academy of Sciences), Qing ZANG (Institute of Plasma Physics, Chinese Academy of Sciences), Haiqing LIU (Institute of Plasma Physics, Chinese Academy of Sciences), Wei GAO (Institute of Plasma Physics, Chinese Academy of Sciences), Zhenwei WU (Institute of Plasma Physics, Chinese Academy of Sciences), Junling CHEN (Institute of Plasma Physics, Chinese Academy of Sciences), Xianzu GONG (Institute of Plasma Physics, Chinese Academy of Sciences), Liqun HU (Institute of Plasma Physics, Chinese Academy of Sciences)
• 10:31
6.51 Imaging of Divertor Strike Point Splitting in RMP ELM Suppression Experiments 2h

Fast visible imaging of the lower divertor surface has been implemented to study the structure and dynamics of lobes induced by resonant magnetic perturbations (RMP) in ELM suppression experiments in DIII-D. The best compromise between amount of light and sharp imaging was obtained using emission at 601 nm that in ionizing plasmas is due to molecular deuterium emission from the Fulcher-α band. Multiple spatially resolved peaks in the D2 emission, taken as a proxy for the particle flux, are readily resolved during RMPs, in contrast to the heat flux measured by infrared cameras, which shows little spatial structure in ITER-like conditions. The 25 mm field lens provides high spatial resolution from the centerpost to the outer shelf over 50° toroidally that overlaps the field of view of the IRTV. The image is coupled to a Phantom 7.3 camera using a Schott wound fiber bundle, providing high temporal resolution that allows the lobe dynamics to be resolved between ELMs and across ELM suppression onset. These measurements are used to study the heat and particle flux in 3D magnetic fields, and to validate models for the plasma response to RMPs. *Work supported by U.S. DOE under DE-FG02-07ER54917, DE-FG02-05ER54809, DE-FC02-04ER54698, DE-AC52-07NA27344, DE-NA0003525, and DE-AC04-94AL85000.

Speakers: Richard Moyer (University of California San Diego), I.O. Bykov (University of California San Diego), D.M. Orlov (University of California San Diego), T.E. Evans (General Atomics), J.S. Lee (University of California Los Angeles), A.M. Teku (Oregon State University), M.E. Fenstermacher (LLNL), M. Makovski (LLNL), H.Q. Wang (Oak Ridge Associated Universities), J. Watkins (Sandia National Laboratories), W. Wu (General Atomics)
• 10:31
6.52 A multichannel gated neutron detector with reduced afterpulse rate for neutron time-of-flight measurements in strong x-ray circumstances 2h

Gated-photomultiplier-tubes (gated-PMT’s) with increased robustness against background noises due to the hard x-ray incidence have been implemented on the 600-channel neutron time-of-flight (nTOF) detector at Institute of Laser Engineering (ILE), Osaka University. This diagnostic uses 600 individual neutron detectors consisting of a plastic scintillator and a liner-focused PMT, allowing to obtain a large detection area with long flight path (13.5 m). A very simple gating circuit has been developed to gate out the primary x-ray peak and measure the subsequent neutron signals without causing the anode current saturation. By applying a reverse potential between the cathode and first dynode (d1), we succeeded in suppressing subsidiary signals called “after pulse” produced after the main pulse (see Fig. 1), mainly due to ionic feedback to the photocathode. Cathode-d1 voltages of all the PMT’s are simultaneously switched by only one switching circuit module coupled with a digital delay pulse generator (e.g. DG645) and a DC power supply. The switching circuit provides + 200-V precisely defined squire pulse with a reasonably steep front of 80 ns. A high cut-off ratio of anode current of more than 103 can be obtained under constant illumination in the 'on' and 'off' conditions. Our design

Speaker: Yuki Abe (Institute of Laser Engineering, Osaka University)
• 10:31
6.53 Calibration of a Langmuir probe in magnetized plasma using interferometry 2h

Langmuir probe diagnostic is one of the widely used techniques for plasma parameters measurements. While the construction and installation of a probe usually represent no significant complications, the data analysis encounters multi-layered challenges. All parts of an IV characteristic are bound to more than one plasma parameter, which means that self-consistent calculations are needed and cross errors can never be completely excluded. A theory for data interpretation in the presence of a magnetic field is tested for a cylindrical Langmuir probe in a linear low-temperature plasma device Aline. The probe is placed on a 3D manipulator parallel to the magnetic field direction and a position scan is performed. Tests are done in a capacitive radio-frequency (RF) discharge at 3.5 cm above an RF antenna. Typical RF sheath size around the antenna is in the order of few cm, depending on the neutral gas pressure, coupled power and magnetic field strength, and the sheath region is avoided to exclude strong RF perturbations. Using the theory electron densities are obtained from the current values at the plasma potential. Results are calibrated by line-integrated density measurements of a 26.5 GHz microwave interferometer MWI 2650 from Miwitron and reasonable agreement is observed.

Speakers: Mariia Usoltceva (Ghent University), Eric Faudot (Université de Lorraine), Stéphane Devaux (Université de Lorraine), Stéphane Heuraux (Université de Lorraine), Roman Ochoukov (Max-Planck-Institut für Plasmaphysik), Kristel Crombé (Ghent University), Jean-Marie Noterdaeme (Ghent University)
• 10:31
6.54 Frequency sweep linearization of FM reflectometry 2h

Frequency Modulation reflectometer requires that the whole frequency range is linearly swept. For this purpose, Voltage Controlled Oscillator (VCO) is finely tuned to accomplish the linear frequency sweep. However many components such as frequency multiplier, power amplifier, filter, etc, distort the frequency sweep characteristics. In addition, the frequency dispersion of the wave guide also distorts the frequency sweep. In KSTAR Q band reflectometer, a slightly over-sized wave guide (Ka band) is used for the microwave transmission. So the frequency sweep is significantly affected by the frequency dispersion of the wave guide. Although this distortion can be avoided by using a sufficiently over-sized wave guide, it is not easy to replace the existing wave guide installed inside of a heavily packed port of super conducting magnet tokamak. In this presentation, the distortion of frequency sweep due to the wave guide is quantitatively assessed and a compensation algorithm is devised. The algorithm is explained in detail and the compensated and non-compensated results are compared.

Speaker: Seong-Heon Seo (NFRI)
• 10:31
6.55 Table benchmark and simulation test of EAST MIR system 2h

Microwave imaging reflectometry (MIR) system for EAST tokamak has been constructed with 96 channels (12 poloidal x 8 radial). The illumination beam of MIR has eight independent frequencies which can be flexibly adjusted in W band (75 - 105 GHz). The receiver system has eight antennae aligned in the vertical direction. The integrated electronic systems have been tested. We also set up an artificial simulation system using a radius adjustable rotating plate equipped with metallic grating-like structure to simulate cutoff-layer and the density fluctuation in plasma to benchmark performance of EAST MIR in laboratory. The characteristics of EAST MIR will be given.

Speakers: Wang Liao (University of Science and Technology of China), Jinlin Xie (University of Science and Technology of China), Chengming Qu (University of Science and Technology of China), Xinhang Xu (University of Science and Technology of China), Feixue Gao (University of Science and Technology of China), Ning Kang (University of Science and Technology of China), Xianzi Liu (University of Science and Technology of China), Yilun Zhu (University of California at Davis), Calvin Domier (University of California at Davis), Neville Luhman (University of California at Davis)
• 10:31
6.56 Upper Wide Angle Viewing System Design for ITER 2h

One of several diagnostic systems being developed by the US is the Upper Wide Angle Viewing System (UWAVS) which provides real-time, simultaneous visible and infrared images of the ITER divertor regions via optical systems located in five upper ports. The primary design challenge of the UWAVS is maximizing system performance while surviving the severe electromagnetic and nuclear ITER environment. A first mirror material study was conducted, determining that single crystal molybdenum was the best choice for the first two mirrors of the in-vessel assembly. A fail open, bellows actuated shutter with cross pivot flexure design was determined to be the most reliable mechanism to protect the foremost plasma facing mirror. A geometrically representative glow discharge mirror cleaning system was designed and tested to maximize cleaning effectiveness while minimizing optical degradation of the first two plasma facing molybdenum mirrors. R&D efforts, technical challenges and issues, and design and analysis results are presented.This work is supported by US DOE Contract No. DE-AC02-09CH11466 under subcontract number S013437-C. The views and opinions expressed herein do not necessarily reflect those of the ITER Organization.

Speaker: Matthew Smiley (General Atomics)
• 14:00 16:00
Session #7, Tuesday Afternoon Invited Talks, Chair: J. Frenje
• 14:00
7.1 An Imaging Neutral Particle Analyzer for Precision Measurements of the Confined Fast Ions in Fusion Experiments 30m

A novel scintillator-based imaging neutral particle analyzer (INPA), which provides energy-resolved radial profiles of confined fast ions, has been designed and installed on the DIII-D tokamak. The system measures charge-exchanged energetic neutrals by viewing an “active” neutral beam through a 1D pinhole camera with a rear collimating slit that defines the neutral particle collection sightlines and radial positions probed in the plasma. The incident neutrals are ionized by ultra-thin carbon stripping foils of 10 nm thickness with the local tokamak magnetic field acting as a magnetic spectrometer to disperse the ions onto a scintillator. The strike position on the phosphor is determined by the fast ion energy and sightline, while the intensity of emitted light from the phosphor is proportional to the ion flux. Fast camera measurements of the scintillator provide 2D images of the escaping neutrals mapped to energy and radial position in the plasma. The INPA system images a broad radial range from the plasma core to edge and deuterium energies up to 80 keV, with energy resolution of ~7.5 keV and pitch resolution of <5°. Initial data demonstrates that the system has exceptionally good signal to noise and provides unprecedented details of phase space dynamics.

Speakers: Xiaodi Du (University of California, Irvine), Michael Van Zeeland (General Atomics), William Heidbrink (University of California, Irvine)
• 14:30
7.2 Reconstruction of the cold fuel shell in ICF experiments using neutron imaging at the NIF 30m

Neutron, gamma-ray and x-ray imaging are important diagnostic tools at the National Ignition Facility (NIF) for measuring the two-dimensional (2D) size and shape of the neutron producing region, for probing the remaining ablator, and measuring the extent of the DT plasmas during the stagnation phase of Inertial Confinement Fusion (ICF) implosions. Novel analysis tools for primary fusion and down-scattered (neutrons that have scattered off the compressed ICF shell) neutron images observed with the NIF have been developed that allow the forward reconstruction of the fuel density profile. This is extremely important with far reaching impact in this field as this work help fills a critical diagnostic gap in cryogenic DT experiments at NIF, namely the diagnoses of the cold compressed shell. It is currently believed that asymmetries and defects in the shell are leading factors in performance degradation in ICF implosion, and our ability to diagnose them is critical in order to work toward improvements. The recently commissioned second primary neutron image line of sight (there are now a polar and an equatorial primary image) has allowed us to perform a 3D reconstruction of the primary hotspot using these two views. This work promises 3D tomography of both the hot burning plasma and the compressed shell in NIF explosions with additional lines of sight. We present the detailed algorithms used for this characterization, and the resulting reconstructed cold fuel shells from experimental data collected at NIF.

Speakers: Petr Volegov (LANL), Steve Batha (LANL), Daniel Casey (LLNL), Christopher Danly (LANL), David Fittinghoff (LLNL), Verena Geppert-Kleinrath (LANL), Gary Grim (LLNL), Frank Merrill (LANL), Carl Wilde (LANL)
• 15:00
7.3 A Quartz-based Cherenkov Radiator for High Precision Time-of-Flight Measurement of DT Fusion Gamma and Neutron Spectra 30m

A quartz based Cherenkov radiator has been implemented at the National Ignition Facility (NIF) to provide a new high precision measurement of the spectrum of 14.1 MeV DT fusion neutrons. This detector has two benefits over traditional scintillator-based nToFs. (1) it enables a high precision (<50ps) co-registered measurement of both a thresholded gamma spectrum and the neutron spectrum on a single record; other methods typically require gamma and neutron signals to be co-registered via other diagnostics and/or dedicated timing experiments. (2) the temporal width of the instrument response function (IRF) is reduced to < 1.0ns thereby reducing the uncertainty in the Brysk ion temperature derived from the width of the measured neutron spectrum. Analysis of co-registered gamma and neutron data from NIF DT implosions on multiple lines-of-sight indicate that the bulk vector velocity of the implosion hot-spot can be determined to within 5 km/s, while analysis of the neutron spectrum indicates the uncertainty in the ion temperature due to the IRF is reduced to approx. 0.1keV. LLNL-ABS-744335 This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

Speakers: Alastair Moore (LLNL), Daniel Sayre (LLNL), David Schlossberg (LLNL), Edward Hartouni (LLNL), Robert Hatarik (LLNL), Gary Grim (LLNL), Mark Eckart (LLNL), Jaben Root (LLNL), Cory Waltz (LLNL), Bart Beeman (LLNL), Francisco Barbosa (LLNL), Michael Rubery (LLNL)
• 15:30
7.4 Utilization of outer-midplane collector probes with isotopically enriched tungsten tracer particles for impurity transport studies in the scrape-off layer of DIII-D 30m

Triplet sets of replaceable graphite rod collector probes (CPs), each with collection surfaces on opposing faces oriented normal to the magnetic field, were inserted at the outboard mid-plane of DIII-D to understand divertor tungsten (W) transport in the Scrape-Off Layer (SOL). Each CP collects particles along field lines with different parallel collection lengths (determined by the rod diameters and SOL radial transport) giving radial profiles from the main wall inward to R-Rsep~6cm. Rutherford backscatter spectrometry of the CPs provided areal density profiles of elemental W coverage. Higher peak W content measured on the probe face connected along the field lines to the inner divertor indicate higher concentration of W in the plasma upstream of the CP. The CPs were also used in a first-of-a-kind experiment using isotopically-enriched, W-coated divertor tiles. Laser ablation mass spectroscopy validates the isotopic tracer technique through analysis of CPs exposed during L-mode discharges with the outer strike point on the enriched W tile inserts. Results provided quantitative information on the W source and transport from specific poloidal locations within the lower outer divertor region. US DOE support DE-AC05-00OR22725, DE-FG02-07ER54917, DE-FC02-04ER54698, DE-NA0003525.

Speakers: David Donovan (University of Tennessee-Knoxville), Ezekial A. Unterberg (Oak Ridge National Laboratory), William R. Wampler (Sandia National Laboratory), Michael P. Zach (Oak Ridge National Laboratory), Dmitry Rudakov (University of California-San Diego), Jonah D. Duran (University of Tennessee-Knoxville), Shawn Zamperini (University of Tennessee-Knoxville), David Elder (University of Toronto Institute for Aerospace Studies), Peter C. Stangeby (University of Toronto Institute for Aerospace Studies), Tyler W. Abrams (General Atomics), Jack Nowotarski (University of Tennessee-Knoxville)
• 16:00 18:00
Session #8, Tuesday Afternoon Poster Session
• 16:00
8.1 Measurement of the fast electron bremsstrahlung emissions on J-TEXT 2h

The measurement of supper thermal electron population is an important issue for the study of runaway electrons in the low density discharges or during the disruptions in tokamak plasmas. The fast electron bremsstrahlung (FEB) emissions resulted from the interaction between the low energy runaway electrons and the bulk plasma can provide significant information on the runaway generation process. A multi-channel FEB diagnostics has been developed on the J-TEXT tokamak. The FEB system observe the FEB emissions in the energy range of 30~300keV. It can monitor the runaway generation process since its beginning of formation.

Speakers: Zhongyong Chen (Huazhong University of Science and Technology), Huaiyi Yang (Huazhong University of Science and Technology)
• 16:00
8.2 In-situ surface diagnostics for magnetic fusion 2h

Important plasma-surface processes in burning plasmas include erosion due to physical and chemical sputtering, material redeposition and transport, mechanical failure, and other unique topics such as fuel recycling, tungsten fuzz formation, tritium retention, all of which are wall-material dependent and highly dynamic. It is also anticipated that better understanding through in-situ measurements will lead to better plasma performance and plasma-facing material development. Although a suite of surface diagnostics exists for material science, chemistry and others, very few of them can be directly applied to in-situ surface diagnostics due to the hostile environment of burning plasmas and the presence of tesla magnetic fields. Fusion neutrons only make the problem more challenging. Here we review the existing fusion surface diagnostics, as well as current status of surface measurements that can potentially be adapted to in-situ monitoring or characterization of particle flux, species identification, erosion rate, particle recycling, energy flux, and their temporal evolutions. Examples from several fusion devices and plasma experiments will be given. New opportunities for in-situ diagnostics associated with novel material interrogation techniques will be emphasized.

Speakers: Zhehui Wang (Los Alamos National Laboratory), Tyler Abrams (General Atomics), Sebastijan Brezinsek (Forschungszentrum Jülich GmbH), Vincent Donnelly (University of Houston), Mark Hoffbauer (Los Alamos National Laboratory), Zhenhua Hu (Institute of Plasma Physics, Chinese Academy of Sciences), Peter Lang (MPI für Plasmaphysik), Guangnan Luo (Institute of Plasma Physics, Chinese Academy of Sciences), Yongqiang Wang (Los Alamos National Laboratory), Kevin Woller (MIT Plasma Science & Fusion Center)
• 16:00
8.3 OMEGA Supersonic Gas-Jet Plasma Characterization with Thomson Scattering 2h

A supersonic gas-jet target platform has been activated on the OMEGA laser. The plasma formed using a gas-jet target and ~3 kJ of UV energy from the OMEGA Laser System was characterized using 2ω Thomson scattering. Thomson scattering provided accurate time-resolved measurements of plasma conditions including electron density, plasma temperature, and ionization state. Plasma conditions include electron temperatures in the 0.5-keV to 1-keV range and electron densities between 1 × 10^19cm^3 and 9 × 10^19cm^3 in a nitrogen plasma. The measurements made using Thomson scattering are then compared with the results of the radiation–hydrodynamics code HYDRA. These initial measurements demonstrate the capabilities of the OMEGA gas-jet as a platform for future laser–plasma interaction science. This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0001944.

Speakers: Aaron Hansen (Laboratory for Laser Energetics), Daniel Haberberger (Laboratory for Laser Energetics), Dustin Froula (Laboratory for Laser Energetics)
• 16:00
8.4 Development for neutron emission spectroscopy diagnostics for EAST Deuterium operation 2h

Measurements of fusion neutron spectrometry is a useful diagnostic for DD neutron yield from 109 to 1015 n/s for EAST deuterium plasma discharges with NBI, LHWl, ICRF heating and their combination. A suite of compact neutron spectrometers, based on liquid scintillators and a stilbene crystal detector has been implemented on EAST for lower yield neutron measurements, and the ion temperature values were obtained from the deduced neutron spectra by a forward fitting method applied to the measured pulse height spectra. The neutron time-of-flight enhanced diagnostics (TOFED) spectrometer has been installed at the J port of EAST in order to study the behavior of fast ions. The new design is shown to enhance the discrimination capability and will provide fusion neutron spectra with reduced admixture of multiple scattering events. A new fully digital data acquisition system with on-board CFD timing function has been adopted and can provide a high count rate capability up to about 1 MHz/channel of the spectrometer. During the EAST 2017 summer campaign, synergized diagnostics from the TOFED and liquid scintillator spectral measurements were performed for the first time and the different components of neutron spectra are successfully separated at EAST plasmas with NBI heating.

Speakers: Tieshuan Fan (Peking University), Lijian Ge (Peking University), Zhimeng Hu (Peking University), Yimo Zhang (Peking University), Jiaqi Sun (Peking University), Xingyu Peng (Peking University), Tengfei Du (Peking University), Zhongjing Chen (Peking University), Xufei Xie (Peking University), Xing Zhang (Peking University), Xi Yuan (Peking University), Xiangqing Li (Peking University), Jinxiang Chen (Peking University), Guoqiang Zhong (Institute of Plasma Physics, CAS ), Linqun Hu (Institute of Plasma Physics, CAS ), Shiyao Lin (Institute of Plasma Physics, CAS ), Baonian Wan (Institute of Plasma Physics, CAS ), Giuseppe Gorini (University of Milano-Bicocca), Massimo Nocente (University of Milano-Bicocca), Marco Tardocchi (Instituto di Fisica del Plasma "P. Caldirola", Milano ), Jane Kallne (Uppsala University )
• 16:00
8.5 Forward modeling for the development of a Laser-Induced Rydberg Spectroscopy diagnostic on NSTX-U 2h

In fusion devices, subtle changes at the plasma edge (pedestal and scrape-off layer) can have a dramatic influence on confinement performance and anomalous transport properties of the plasma. In order to better understand physical processes happening in this region, we describe a detailed analysis of a novel diagnostic allowing the direct measurement of the local radial electric fields in the pedestal region in NSTX-U. Using a tunable probe laser to deplete the naturally populated n=3 level to a Rydberg state and the existing Thomson-scattering optics, it is shown that the local electric field can be measured through the Stark induced resonances observed as a dip in the D_α emission. The proposed diagnostic gives measurements resolved both in space and time with a 10 ms time-step. Using our simulated absorption spectrum; a precision of ~2 kV/m in regions with a local electric field of 50 kV/m is predicted when we account for density fluctuations and statistical uncertainties due to the acquisition and fitting process.

Speakers: Loïc Reymond (Swiss Plasma Center - EPFL), Ahmed Diallo (Princeton Plasma Physics Laboratory - Princeton University), Vladislav Vekselman (Princeton Plasma Physics Laboratory - Princeton University)
• 16:00
8.6 Preliminary design on diagnostic port plug for CFETR 2h

Currently Chinese Fusion Engineering Test Reactor (CFETR) has completed its physical design and started the phase of engineering design. To make transfer easier from Phase I to Phase II with the same machine, a larger size with R = 6.6 m/a = 1.8 m, BT = 6–7 T has been chosen. Diagnostic port plug, as one important part for reactor, will provide a common platform to support or contain variety diagnostic systems that require an external radial access to the plasma. Now we are considering two diagnostic port plug models, one is ITER-like case which is similar to the ITER diagnostic port plug structure, and another one is towards DEMO case, as a new way to DEMO. In this paper, we present a preliminary design and study for CFETR ITER-like case diagnostic port plug. Firstly, the design justification is given and equal diagnostic port plug model is designed; Then, EM loads and total displacements during a 32ms disruption of a 19.6 MA plasma current have been shown; at last, some important issues, including diagnostic port plug installation/removal and remote handing for maintains, have been discussed.

Speakers: Gongshun Li (Shenzhen University), Yao Yang ( Institute of Plasma Physics, Chinese Academy of Science (ASIPP)), Xiang Gao (Shenzhen University;Institute of Plasma Physics, Chinese Academy of Science (ASIPP)), Jiangang Li, Xiaodong Lin (Shenzhen University;Institute of Plasma Physics, Chinese Academy of Science (ASIPP)), Jianjun Huang (Shenzhen University;Institute of Plasma Physics, Chinese Academy of Science (ASIPP)), Huibin Sun (Shenzhen University;Institute of Plasma Physics, Chinese Academy of Science (ASIPP)), Guoqiang Li (Institute of Plasma Physics, Chinese Academy of Science (ASIPP)), Qingsheng Hu (Institute of Plasma Physics, Chinese Academy of Science (ASIPP)), Yumin Wang (Institute of Plasma Physics, Chinese Academy of Science (ASIPP)), Xiang Han (Institute of Plasma Physics, Chinese Academy of Science (ASIPP)), Shaocheng Liu (Institute of Plasma Physics, Chinese Academy of Science (ASIPP)), Erhui Wang (Institute of Plasma Physics, Chinese Academy of Science (ASIPP))
• 16:00
8.7 Time-Resolved and Multiple-Angle Thomson Scattering on Gas Puff Z-Pinch Plasmas 2h

The conditions and dynamics of neon gas puff z-pinch plasmas at pinch time are studied on COBRA, Cornell’s pulsed power generator (current rise time of ~240 ns and ~0.9 MA peak current). A 526.5 nm, 10 J Thomson scattering diagnostic laser enables probing of the plasma conditions of these implosions with both spatial and temporal resolution. The use of two laser pulses--both 3 ns in duration--that can be separated by up to 10 ns allows observation of time-resolved spectra for a total consecutive time of 6 ns. This setup, at 90° to the laser with a field of view of 0.4 mm on-axis, provides sub-nanosecond resolution of pinch evolution through stagnation. Two additional time-gated collection optics, one at 90° to the laser path and one at 30°, probe a 4 mm field of view across the axis. Based on whether the collection angle (and therefore the k vector) is large or small, the spectral feature dependence on the electron density is, respectively, more or less sensitive to variations in density [1]. By comparing the spectra from two angles, it is possible to ascertain an approximate electron density from the ion acoustic feature.
[1] D. Foula et al., PRL 95, 195005 (2005).
*Work supported by NNSA SSAP under DOE Cooperative Agreement No. DE-NA0001836 and LLNL subcontract no. B619181.

Speakers: Sophia Rocco (Cornell University), Jacob Banasek (Cornell University), William Potter (Cornell University), David Hammer (Cornell University)
• 16:00
8.8 Helicon Power Source Analysis of the Prototype Material Exposure eXperiment (Proto-MPEX) using Fluoroptic Probes* 2h

Proto-MPEX is a prototype design for the Material Plasma Exposure eXperiment (MPEX), a steady-state linear device being developed to study plasma material interactions (PMI). The primary purpose of Proto-MPEX is developing plasma heating source concepts for MPEX, which include a 13.56 MHz half-turn copper helicon antenna surrounding an aluminum nitride (AlN) window, whose strong electromagnetic (EM) fields inhibit reliable data collection of the helicon region from most installed diagnostics. Fluoroptic probes (FPs) are unique thermometric diagnostics composed of an optical fiber with a temperature sensitive phosphorescent sensor tip that are immune to EM field interference. Five fluoroptic probes are installed under the antenna such that they are in thermal contact with the AlN window. These FPs estimate heat loss from the plasma under the helicon antenna via observed temperature increases on the helicon window. Analyzed in conjunction with installed thermocouples (TCs), double Langmuir probes/Mach probes (DLPs/MPs), and SOLPS modeling, the FPs quantify the helicon plasma, identifying dominant loss mechanisms for specific machine operating parameters. *This work was supported by the U.S. D.O.E. contract DE-AC05-00OR22725.

Speakers: M. Showers (ORNL/UT-Knoxville), T.M. Biewer (ORNL), J.F. Caneses (ORNL), J.B.O. Caughman (ORNL), D.C. Donovan (UT-Knoxville), R.H. Goulding (ORNL), A. Lumsdaine (ORNL), N. Kafle (ORNL/UT-Knoxville), L. Owen (ORNL), J. Rapp (ORNL)
• 16:00
8.9 Simultaneous measurements of turbulent Reynolds stresses and particle flux in both parallel and perpendicular directions in a linear magnetized plasma device 2h

We report temporally resolved, simultaneous measurements of the turbulent Reynolds Stresses in both the parallel and perpendicular directions and the corresponding particle fluxes in the fusion relevant cylindrical magnetized plasma device Controlled Shear Decorrelation eXperiment (CSDX). CSDX simulates the plasma conditions of and multiple plasma instabilities that can arise in the scrape off layer of fusion devices. In this study, we designed and used a 6 tip - Langmuir probe in a novel yet simple design to simultaneously measure all the three dimensional components (radial, azimuthal and axial) of fluctuations in velocity from the floating potentials and plasma densities with high temporal resolution. From these, we calculated the parallel and perpendicular Reynolds stress and the particle fluxes in addition to the density and potential spectra and the cross phase between different quantities. In one fast radial scan of the probe, we can achieve radial profiles of all the aforementioned plasma quantities, which are extremely useful for studying plasma turbulence due to multiple instabilities. We have also cross checked the time averaged velocity profiles from the probe with laser induced fluorescence measurements of the mean plasma velocity for common plasma source parameters.

Speakers: Saikat Chakraborty Thakur (University of California San Diego), Rongjie Hong (University of California San Diego), George Tynan (University of California San Diego)
• 16:01
8.10 Improvements of collective scattering measurements by polarimeter-interferometer on J-TEXT tokamak 2h

In our previous works, the multichannel three-wave polarimeter-interferometer system (POLARIS) on J-TEXT tokamak has been exploited to measure far-forward collective scattering (FCS) from electron density fluctuations [1]. Most recently, some substantial improvements have been completed. Firstly, the data processing is optimized, so that the low-frequency density fluctuations (<20kHz) could be obtained, which is covered by the intermediate frequency (IF) in previously. By use of the new data processing, low-frequency density fluctuations associated with tearing mode and zonal flow have been observed. Secondly, the effect of refraction of incident beam passing plasma on FCS measurements has been considered, so that the identification of propagation direction of density fluctuation is available for measuring channels at edge region, where the refraction angle is significant. And two different quasi-coherent density fluctuations propagating in ion and electron direction respectively have been observed in J-TEXT Ohmic plasma. gezhuang@ustc.edu.cn
[1] P. Shi et al., Rev. Sci. Instrum. 87, 11E110 (2016).
[2] Chen, J et al., Rev. Sci. Instrum. 85, 11D303 (2014).
[3] Zhuang, G et al., Nuclear Fusion 51.9, 094020 (2011).

Speakers: Peng Shi (Huazhong University of Science and Technology), Ge Zhuang (University of Science and Technology of China), Qingshuang Qiu (Huazhong University of Science and Technology), Jie Chen (University of California Los Angeles), Yinan Zhou (Huazhong University of Science and Technology)
• 16:01
8.11 JET Diagnostic Enhancements Testing and Commissioning in Preparation for DT Operations 2h

In order to optimize the scientific exploitation of JET during the upcoming deuterium-tritium experiments, a set of diagnostic systems is being enhanced. These upgrades focus mainly on the experimental and operational conditions expected during tritium campaigns. It should be stressed that measurements relevant for burning plasmas are specifically targeted. Previously non-existing capabilities, such as a current measurement system fully covering all poloidal field circuits, are described in detail. Instrument descriptions, performance prediction, testing and initial commissioning results of these systems are presented. This work has been carried out within the framework of the EUROfusion Consortium and has received funding from the Euratom research and training programme 2014-2018 under grant agreement No 633053. The views and opinions expressed herein do not necessarily reflect those of the European Commission.

Speakers: Joao Figueiredo (EUROfusion Programme Management Unit and Instituto de Plasmas e Fusão Nuclear, Instituto Superior Técnico, Universidade de Lisboa ), Andrea Murari (EUROfusion Programme Management Unit and Consorzio RFX (CNR, ENEA, INFN, Universita’ di Padova, Acciaierie Venete SpA)), Christian Perez Von Thun (EUROfusion Programme Management Unit and Consorzio RFX (CNR, ENEA, INFN, Universita’ di Padova, Acciaierie Venete SpA)), Daniele Marocco (Unità Tecnica Fusione - ENEA C. R. Frascati), Marco Tardocchi (IFP-CNR), Francesco Belli (Unità Tecnica Fusione - ENEA C. R. Frascati), Manuel García Muñoz (Universidad de Sevilla), Antonio Silva (Instituto de Plasmas e Fusão Nuclear, Instituto Superior Técnico, Universidade de Lisboa), Teddy Craciunescu (The National Institute for Laser, Plasma and Radiation Physics), Patrick Blanchard (Ecole Polytechnique Fédérale de Lausanne (EPFL), CRPP), Itziar Balboa (CCFE, Culham Science Centre), Nick Hawkes (CCFE, Culham Science Centre), Ivo Samuel Carvalho (Instituto de Plasmas e Fusão Nuclear, Instituto Superior Técnico, Universidade de Lisboa), Balazs Tal (Wigner Research Centre for Physics), João Bernardo (JET Exploitation Unit and Instituto de Plasmas e Fusão Nuclear, Instituto Superior Técnico, Universidade de Lisboa ), Izabella Zychor (Narodowe Centrum Badań Jądrowych (NCBJ))
• 16:01
8.12 Relative intensity calibration of KSTAR beam emission spectroscopy by using fast visible CMOS camera 2h

Relative intensity calibration for the KSTAR beam emission spectroscopy (BES) system is successfully achieved with a fast visible CMOS camera. The KSTAR BES system with 2D array (4×16) avalanche photodiode (APD) detectors is allowed to move its spatial position of measurements and rotate its orientation to study plasma turbulence at various spatial positions. A proper relative intensity calibration, thus, requires beam-into-gas shots for all possible measurement positions, which becomes not only laborious but also shortening the lifetime of the beam dump, since the optical alignments are altered as the position is changed. The KSTAR BES system is equipped with a fast visible CMOS camera sharing the most of the same optics system with the APD detectors, resulting in that some of the CMOS pixels have the same optical axes with the APD detectors. Based on this fact, we propose a relative intensity calibration technique for all possible positions of the APD detectors based on the CMOS camera signals with only few beam-into-gas-shots. Our proposed technique is examined against experimental data and found to be applicable at least for the KSTAR BES system.

Speakers: Jaewook Kim (KAIST), Yong-un Nam (NFRI), Mate Lampert (Wigner RCP), Sandor Zoletnik (Wigner RCP), Young-chul Ghim (KAIST)
• 16:01
8.13 Ion cyclotron emission (ICE) study on the ASDEX Upgrade tokamak 2h

Ion cyclotron emission (ICE) is a commonly observed feature of magnetized toroidal plasmas in the presence of fast ions. It is generally agreed that this emission is caused by an inverted velocity distribution of confined fast ions originating from either neutral beam injection (NBI), fusion reactions, or acceleration by waves in the ion cyclotron range of frequencies (ICRF). As a result, ICE can provide a non-perturbing measure of the state of confined alpha particles in a deuterium-tritium fusion device, such as ITER or DEMO. The ICE diagnostic on ASDEX Upgrade (AUG) is capable of detecting ICRF fields emitted by plasma. It consists of a pair of fast digitizer channels (125 MHz sampling rate), which are connected to a pair of B-dot probes inside the AUG torus, on the low field side (LFS). These probes are oriented such that the wave number and the mode polarization can be estimated. The frequency spectra reveal the radial location of ICE origin: the most common ICE originates from the LFS plasma region and is likely to be due to fast NBI ions. Signals consistent with fusion proton-driven emission are also observed, most commonly originating in the edge. However, under certain conditions, core ICE is also detected, with the fusion protons being the likely emission driver.

Speakers: Roman Ochoukov (Max Planck Institute for Plasma Physics), Volodymyr Bobkov (IPP-Garching), Helmut Faugel (IPP-Garching), Manuel Garcia-Munoz (University of Seville, Spain), Benedikt Geiger (IPP-Garching), Ken McClements (3Culham Center for Fusion Energy), Dmitry Moseev (IPP-Greifswald), Stefan Nielsen (Technical University of Denmark), Philip Schneider (IPP-Garching), Markus Weiland (IPP-Garching), Jean-Marie Noterdaeme (IPP-Garching)
• 16:01
8.14 Solid-state framing camera operating in interferometric mode 2h

A high speed solid-state framing camera has been developed which can operate over a wide range of photon energies. This camera measures the change in the index of refraction of a semiconductor when photons with energies higher than the bandgap are incident upon it. This instrument uses an binary grating in front of the semiconductor to impose a corresponding grating in the semiconductor when photons higher than the band gap pass through the grating and are absorbed in the semiconductor, thereby producing a spatially dependent change in the index of refraction. A probe beam is then scattered off of this grating to measure the x-ray signal incident on the semiconductor. In this particular instrument the zero order scattered probe beam is attenuated and interfered with the higher orders to produce an interferometric image of the phase grating produced inside the semiconductor. This camera has been tested at 3.1 eV and 4.5 keV.

Speakers: Kevin Baker (LLNL), Paul Steele (LLNL), Rick Stewart (LLNL), Steve Vernon (LLNL), Warren Hsing (LLNL), Bruce Remington (LLNL)
• 16:01
8.15 Synthetic Diagnostic for Electron Cyclotron Emission Imaging 2h

Synthetic diagnostics are aimed at simulating the responses of diagnostic systems under real experimental scenarios and are the key to drawing quantitative inferences from experimental data. The synthetic ECEI diagnostic is suitable to evaluate the improvement arising from the application of Field Curvature Adjustment (FCA) lenses in the design of the upgraded EAST ECEI system. Previously, a curved image plane is inevitable in the optics system with only convex lenses, which leads to stronger crosstalk between vertically adjacent channels and strongly limits the vertical channel resolution of the imaging system. The synthetic ECEI diagnostic results show that, with FCA lenses applied, the upgraded ECEI system has significant advantages to focus on high poloidal wavenumber structures with the aberrations from the spherical surfaces corrected and the various artifacts related to the field curvature suppressed. Also, the synthetic ECEI diagnostics is used for some quantitative calculations to partially decouple the effect of density fluctuations and temperature fluctuations for a given plasma. *Work supported by U.S. DOE Grant FG02-99ER54531

Speakers: Ming Chen (University of California Davis), Yilun Zhu (University of California Davis), Lei Shi (University of California Davis), Chen Luo (University of California Davis), Neville. C. Luhmann (University of California Davis)
• 16:01
8.16 Single-shot, laser-driven x-ray powder diffraction measurements using polycapillary optics to improve laser-to-x-ray conversion efficiency 2h

Single-shot, x-ray diffraction measurements to characterize phase transitions of dynamically compressed, high-Z materials at Mbar pressures require both sufficient photon energy and flux to record data with high fidelity. Besides x-ray lasers and synchrotrons, large-scale laser systems are used to generate brilliant x-ray sources above 10 keV by utilizing line radiation of mid-Z elements. However, the laser-to-x-ray energy conversion efficiency at these energies is low, and broadband thermal x-rays or hot electrons may irradiate the sample and detector, resulting in deleterious background. Polycapillary x-ray optics were employed to both increase the flux on sample as well as the separation between source and sample, resulting in a 20-fold flux increase on the sample versus a conventional pinhole aperture and a reduced background. This facilitates diffraction measurements up to 16 keV at the few-photon signal level. X-ray diffraction measurements were performed using either the Z-Beamlet or Z-Petawatt laser systems at Sandia National Laboratories. This work is supported by Sandia’s LDRD program. Sandia is a multimission laboratory managed and operated by NTESS LLC, a wholly owned subsidiary of Honeywell Int. Inc. for the U.S. DOE NNSA, contract DE-NA0003525. SAND2018-0188A.

Speakers: Marius Schollmeier (Sandia National Laboratories), Tommy Ao (Sandia National Laboratories), Ella Field (Sandia National Laboratories), Patricia Kalita (Sandia National Laboratories), Mark Kimmel (Sandia National Laboratories), Dane Morgan (National Security Technologies, LLC), Patrick Rambo (Sandia National Laboratories), Jens Schwarz (Sandia National Laboratories), Jonathon Shores (Sandia National Laboratories), Ian Smith (Sandia National Laboratories), Christopher Speas (Sandia National Laboratories), John Porter (Sandia National Laboratories)
• 16:01
8.17 Measurement and modeling of bent and flat KAP (001) reflectivity 2h

Measurements were performed on bending magnet beam line 9.3.1 at the Advanced Light Source (Lawrence Berkeley National Laboratory, Berkeley, CA, USA) over the energy range of approximately 2.5 to 8 keV. A dual goniometer endstation was used to measure crystal diffraction properties for the potassium acid phthalate (KAP). The measurement results are subsequently compared to a crystal reflectivity model consisting of theoretical rocking curves calculated using XOP software (a multi-lamellar model for the bent crystals) coupled with a calculation of x-ray beam divergence based on the geometry of the measurement apparatus. We find generally good agreement between the measurements and the model. This work was done by National Security Technologies, LLC, under Contract No. DE-AC52-06NA25946, and by Mission Support and Test Services, LLC, under Contract No. DE-NA0003624, with the U.S. Department of Energy. DOE/NV/03624--0020.

Speakers: Craig Kruschwitz (Nevada National Security Site, Los Alamos Operations), Ming Wu (Sandia National Laboratories), Wayne Stolte (Nevada National Security Site, Livermore Operations), Ken Moy (Nevada National Security Site, Special Technologies Laboratory), Guillaume Loisel (Sandia National Laboratories)
• 16:01
8.18 Low noise fast response power supply of coil for high current modulation 2h

High current modulations are widely required in tokamaks to generate specific magnetic field for plasma confinement, which are challenges for power electronics. For high current modulation, the stray inductance will cause high noise and surge voltage that may damage the power electronics. In addition, it is difficult to ensure both a fast response and a steady evolution. In this paper, a power supply based on insulated gate bipolar transistors (IGBTs) for high current modulation is described. The first stage capacitor bank of higher voltage ensures the current growth rate at the beginning of discharge and plays a role of wave filter later to reduce the noise. The second stage capacitor bank of lower voltage provides the main energy required in discharge. A microcontroller is used to modulate the current by feedback. This power supply can modulate the high current in a coil with low noise and fast response, which has been applied to the poloidal field control and ultrafast reciprocating probe system in SUNIST spherical tokamak.

Speakers: Wenbin Liu (Tsinghua University), Yi Tan (Tsinghua University), Zhe Gao (Tsinghua University)
• 16:01
8.19 Design of tangential multi-energy soft x-ray pin-hole cameras for tokamak plasmas 2h

A new tool has been developed to calculate the spectral, spatial and temporal response of multi-energy soft x-ray (ME-SXR) pinhole cameras for arbitrary plasma densities (ne,D), temperature (Te) and impurity densities (nZ). ME-SXR imaging provides a unique opportunity for obtaining important plasma properties (e.g. Te, nZ and Zeff) by measuring both continuum- and line emission in multiple energy ranges. This technique employs a pixelated x-ray detector in which the lower energy threshold for photon detection can be adjusted independently. The simulations performed assumes a tangential geometry and DIII-D like plasmas (e.g. ne,0~1.0x10^20 m^-3 and Te,0~5 keV) for various impurity (e.g. C, O, SiC, Ar, Ca, Mo and W) density profiles. The computed brightnesses range from few 10^2 to 10^3 counts/ms/pixel depending on the cutoff-energy thresholds, for a maximum count rate of 10 MHz per pixel. These estimates were obtained using FLYCHK x-ray emissivities for arbitrary plasma densities, temperatures between 0.2 and 10 keV, and photon energies between 1 and 50 keV. The XOP code was used to evaluate the x-ray attenuation in various materials (e.g. Be, Al, Si). The typical spatial resolution in the mid-plane is ~1 cm with a photon-energy resolution of 500 eV at a 500 Hz frame rate.

Speakers: Hibiki Yamazaki (The University of Tokyo), Luis F. Delgado-Aparicio (Princeton Plasma Physics Laboratory), Rich Groebner (General Atomics), Kenneth Hill (Princeton Plasma Physics Laboratory), Novimir Pablant (Princeton Plasma Physics Laboratory), Brentley Stratton (Princeton Plasma Physics Laboratory), Philip Efthimion (Princeton Plasma Physics Laboratory), Yuichi Takase (The University of Tokyo), Akira Ejiri (The University of Tokyo), Masayuki Ono (Princeton Plasma Physics Laboratory)
• 16:01
8.20 Two-dimensional radiation profiles during krypton seeding experiments with an infrared imaging video bolometer (IRVB) in KSTAR 2h

Plasma radiation is a crucial parameter for particle and energy transport study in fusion plasmas. Infrared imaging video bolometers (IRVB) can provide radiation profiles of fusion plasmas with noise stability, flat sensitivity and wide viewing range. Since the raw data of IRVB is the sum of local emissivity along the line of sight, tomographic reconstruction for removing line-integration effect is necessary to obtain 2-D cross-sectional radiation profiles. In this study, two-dimensional reconstruction algorithm for KSTAR IRVB was developed using the Phillips-Tikhonov (P-T) method. The reliability of the tomography code was validated by phantom reconstruction tests with various synthetic images. The reconstruction accuracy at divertor was distinctly improved with reduction of IRVB aperture size. In 2017 KSTAR campaign, krypton (Kr) seeding was performed in H-mode plasmas for mitigation or suppression of ELM. The IRVB tomography clearly shows the time evolution of 2-D radiation images after Kr injection. Total radiation power shows that a significant amount of plasma energy is dissipated by Kr radiation. At sufficiently high level of Kr, long-lasting ELM suppression until the end of plasma was also achieved.

Speakers: Juhyeok Jang (Korea Advanced Institute of Science and Technology (KAIST)), Wonho Choe (Korea Advanced Institute of Science and Technology (KAIST)), Byron Jay Peterson (National Institute of Fusion Science (NIFS)), Seungtae Oh (National Fusion Research Institute (NFRI)), Kiyofumi Mukai (National Institute of Fusion Science (NIFS)), Suk-ho Hong (National Institute of Fusion Science (NIFS)), Park Jae Sun (Korea Advanced Institute of Science and Technology (KAIST)), Inwoo Song (Korea Advanced Institute of Science and Technology (KAIST)), Taemin Jeon (Korea Advanced Institute of Science and Technology (KAIST))
• 16:01
8.21 Development of a spectroscopic diagnostic tool  for electric field measurements in IShTAR 2h

IShTAR is a linear device dedicated to the investigation of the edge plasma - ICRF antenna interactions in tokamak edge-like conditions and serves as a platform for a diagnostic development for measuring the electric fields in the vicinity of ICRF antennas. We present here our progress in the development of an optical emission spectroscopy method for measuring the electric fields which concentrates on the changes of the He-I spectral line profiles introduced by the external electrical field, i.e. the Stark effect. To be able to fully control the operating parameters, at the first stage of the study the measurements are conducted on a DC-biased planar electrode installed in the centre of the plasma column in IShTAR’s helicon plasma source. At the second stage, the measurements are performed in the vicinity of IShTAR’s ICRF antenna.

Speakers: Ana Kostc (Ghent University, Faculty of Engineering and Architecture/ Department of Applied Physics/ Research Unit Nuclear Fusion), Ralph Dux (Max-Planck-Institut für Plasmaphysik), Kristel Crombé (Department of Applied Physics, Ghent University), Roman Ochoukov (Max-Planck-Institut für Plasmaphysik), Anton Nikiforov (Department of Applied Physics, Ghent University), Ilya Shesterikov (Max-Planck-Institut für Plasmaphysik), Elijah Martin (Oak Ridge National Laboratory), Jean-Marie Noterdaeme (Department of Applied Physics, Ghent University)
• 16:01
8.22 Design Development of ITER Divertor Langmuir Probes 2h

The Divertor Langmuir Probes (DLP) on ITER will be used for machine control - helping to ascertain attached/detached plasma conditions – as well as for physics studies of the divertor plasma parameters. The severe environment of the divertor region, in particular the high photon radiation loads, presents a particular challenge to the probe design. The photon load averages several W/mm^2 on the plasma facing surfaces, and the total power can reach 20 W/mm^2 on the probe tip. The present design, evolved through several iterations, calls for a flush mounted probe assembly of tungsten and copper components brazed directly to the divertor target PFUs (plasma facing units) or “monoblocks”. Modeling indicates that this solution ensures reasonable temperatures for the passively cooled probes, often cooler than the divertor itself. Details of the present design and thermo-mechanical analysis will be presented, along with the expected system performance. The views and opinions expressed herein do not necessarily reflect those of the ITER Organization.

Speakers: Christopher Watts (ITER Organization), Wei Zhao (Southwest Institute of Physics (SWIP)), Guangwu Zhong (Southwest Institute of Physics (SWIP)), Yuzhong Jin (Southwest Institute of Physics (SWIP))
• 16:01
8.23 Forward weight matrix derivation through Monte-Carlo ray-tracing of KSTAR IRVB 2h

The infrared imaging video bolometer (IRVB) as a foil bolometry technique can be an alternative solution to the conventional resistive bolometer since it has a great advantage in its stability against electromagnetic noise compared with resistive bolometers using a Wheatstone Bridge. As for the data analysis of the IRVB, the plasma 2D radiation profile is not directly converted from the foil image of the IRVB due to the pixel number difference and the line averaged nature of the measurement. However, the forward weight matrix constructing the foil image from the radiation from the plasma can be easily derived through the geometric structure of the system, and the reconstruction process from the foil image to the plasma radiation profile is directly based on the forward weight matrix. So, the precise construction of the forward weight matrix should be an important work. Here we present the way of the forward weight matrix derivation through Monte-Carlo ray-tracing. Compared with the conventional forward weight matrix constructions with only chief rays, this method can provide the most rigorous and precise forward weight matrix since it uses all possible rays at each segment of the foil.

Speakers: Seungtae Oh (NFRI), Juhyeok Jang (KAIST), Byron Peterson (NIFS), Wonho Choe (KAIST), Suk-Ho Hong (NIFS)
• 16:01
8.24 A new method to reconstruct the Bp profile in the Laser-driven Ion-beam Trace Probe (LITP) diagnostics 2h

Xiaoyi Yang, Tianchao Xu, Yihang Chen, Tianbo Wang, Chijie Xiao, Min Xu, Yi Yu, Xiaogang Wang
The Laser-driven Ion-beam Trace Probe (LITP) is a new Bp diagnostic method, firstly proposed in 2014. The basic principle of the LITP method is as follow. Ions generated by laser-driven accelerator are injected into the tokamak, passing through the plasma and finally reached the detector on the vacuum wall. The Bp profile could be reconstructed based on the traces of ions. The ion beam has large energy and pitch angle spread so that the traces of ions with different energies cover a 2D area in the tokamak, and a tomography method is needed to reconstruct 2D Bp profiles. Here a new method based on the solutions of differential equation is proposed. Simulation results and error analysis show that the new method makes the LITP more adjustable and robust.
[1] Yang et al. Rev. Sci. Instrum. 85(11), 11E429 (2014).
[2] Yang et al. Rev. Sci. Instrum. 87(11), 11D610 (2016).

Speaker: Xiaoyi Yang (Peking University)
• 16:01
8.25 Application of the VUV and the soft X-ray systems on JET for the study of intrinsic impurity behavior during neon seeded ILW hybrid discharges 2h

A series of experiments carried out with Ne seeding on JET with the ITER-like-Wall (ILW) suggests increased tungsten release and impurity accumulation as consequences of Ne seeding. For this reason, a detailed study of impurity behaviour together with its control during light gas injection is required. This paper reports on impurity behaviour in a set of hybrid discharges with Ne using the method, which relies on the measurements collected by VUV and soft X-ray diagnostics including the Princeton Instruments survey SPRED spectrometer and the SXR cameras system. Both diagnostics have some limitation. SXR analysis is performed when Te > 1.5-2 keV and it is not clear what species in the plasma are responsible for this radiation , while VUV due to vertical line of sight (LOS) loses most of tungsten radiation. Consequently, only a combination of measurements from these systems are able to provide comprehensive information about high-Z (e.g. tungsten (W)) and mid-Z (Ni, Mo) impurities for their further quantitative diagnosis. Moreover, thanks to the large number of the SXR LOS, determination of 2D radiation profile was also possible. Additionally, experimental results were compared with numerical modelling based on integrated simulations with COREDIV.

Speakers: Natalia Krawczyk (The Institute of Plasma Physics and Laser Microfusion), Agata Czarnecka (The Institute of Plasma Physics and Laser Microfusion), Irena Ivanova-Stanik (The Institute of Plasma Physics and Laser Microfusion), Roman Zagórski (The Institute of Plasma Physics and Laser Microfusion), Clive Challis (CCFE Culham Science Centre ), Scott Silburn (CCFE Culham Science Centre ), Carine Giroud (CCFE Culham Science Centre ), Jonathan Graves (Centre de Recherches en Physique des Plasma), Mervi Mantsinen (Institució Catalana de Recerca i Estudis Avançats (ICREA)), Domenico Frigione (Associazione EURATOM-ENEA, C.R.E. )
• 16:01
8.26 Diagnosing fuel areal-density asymmetries using knock-on deuteron spectra for the 1D campaign at the OMEGA laser facility 2h

Determining fuel areal-density asymmetries is vital to assessing the performance for inertial confinement fusion implosions. The Charged Particle Spectrometry Suite (CPS’s) at the OMEGA facility has been used to infer the fuel areal-density asymmetries in cryogenic deuterium-tritium implosions by measuring the spectrum of knock-on deuterons in different directions. These knock-on deuterons are produced by elastic-scattering between primary DT neutrons and deuterium fuel. The CPS’s, which are located along different lines-of-sight, provide a complimentary measurement to the neutron-based measurements. In this work, we discuss the results from the current effort to use the existing CPS systems to diagnose fuel areal-density asymmetries in cryogenic DT implosions that are part of the 1-D Campaign. Preliminary data analysis reveals that measured fuel areal densities vary up to ~2x along different measurement lines-of-sight, which suggests significant asymmetries and perhaps systematic 3-D effects. This work was supported in part by US DOE (Grant No. DE-FG03- 03SF22691) and LLE (subcontract Grant No. 412160-001G).

Speakers: Raspberry Simpson (Massachusetts Institute of Technology), Johan Frenje (Massachusetts Institute of Technology), Brandon Lahmann (Massachusetts Institute of Technology), Maria Gatu-Johnson (Massachusetts Institute of Technology), Richard Petrasso (Massachusetts Institute of Technology), Chad Forrest (Laboratory for Laser Energetics), James Knauer (Laboratory for Laser Energetics), Sean Regan (Laboratory for Laser Energetics)
• 16:01
8.27 Plasma image acquisition and position detection by using visible camera on EAST 2h

The shape and position of Tokamak plasma play a crucial role in controlling the steady-state operation. Due to the high speed and good visual effect, a high-speed CCD is used for observing the configuration of plasma on Experimental Advanced Superconducting Tokamak (EAST). According to the layout of EAST diagnostics window, the large field of view visible and infrared integrated endoscopy diagnostic system is introduced in this paper. The hardware structure and software design are designed to obtain plasma radiation image with the Phantom V710 high-speed camera. The camera is calibrated with the improved calibration method of Zhang Zhengyou's planar target placed in a vacuum chamber and spatial location is measured. According to the characteristics of plasma image position during the plasma discharge, the Snake algorithm based on the improved watershed is proposed in real-time plasma boundary detection. The boundary is fitted by the curve fitting algorithm based on the least square method and the plasma spatial position is obtained. The EAST experimental results show that the method presented in this paper can realize the expected goals and produce almost perfect effect which is of great significance for better plasma control.

Speakers: Shuangbao Shu (School of Instrument Science and Opto-electronics Engineering, Hefei University of Technology), Chao Liu (School of Instrument Science and Opto-electronics Engineering, Hefei University of Technology), Dongmei Liu (School of Electrical Engineering and Automation,Hefei University of Technology), Meiwen Chen (Institute of Plasma Physics, Chinese Academy of Sciences), Yuzhong Zhang (School of Instrument Science and Opto-electronics Engineering, Hefei University of Technology), Xin Li (School of Instrument Science and Opto-electronics Engineering, Hefei University of Technology)
• 16:01
8.28 Multi-dimensional reconstruction of spatial profiles of plasma conditions in laser-driven ICF implosions 2h

We present multi-dimensional reconstruction of spatial profiles of plasma conditions by analyzing spectrally resolved x-ray image data obtained from OMEGA direct-drive ICF implosions. The targets were spherical plastic shells filled with varying D2-Ar relative and total gas pressures, similar to previous recent experiments [1]. Argon K-shell spectral features were observed primarily between the time of first-shock convergence and slightly before neutron bang time, using a time- and space-integrated spectrometer, streaked crystal spectrometer, and up to three gated multi-monochromatic x-ray imagers (MMI) fielded along quasi-orthogonal lines of sight. The spectrally resolved MMI data were processed to obtain spatially resolved spectra. A non-LTE Ar theoretical spectral database was computed via the Los Alamos Suite of Atomic Codes and used in conjunction with a spectroscopic-quality radiation-transport model. A multi-objective optimization technique [2] is used to extract 3D spatial profiles of plasma conditions (ne, Te, nD, and nAr) in the core. A synthetic-data case is also presented to verify the accuracy of the multi-objective optimization technique.
[1] S. C. Hsu et al., EPL 115, 65001 (2016).
[2] T. Nagayama et al., Phys. Plasmas 19, 082705 (2012). LA-UR-18-20222.

Speakers: Tirtha Raj Joshi (Los Alamos National Laboratory), Peter Hakel (Los Alamos National Laboratory), Scott C. Hsu (Los Alamos National Laboratory), Nelson M. Hoffman (Los Alamos National Laboratory)
• 16:01
8.29 Plasma facing component calorimetry for measurement of shot integrated deposited energy in NSTX-U 2h

The upgrade to the National Spherical Torus eXperiment (NSTX-U) doubles the neutral beam power and enables plasmas to be sustained for up to 5 seconds. The graphite plasma facing components (PFCs) have been re-designed to handle greater heat and energy fluxes than were seen in NSTX using a castellated design. Some scenarios will produce divertor heat fluxes well above the 6-7 MW/m2 the PFCs are designed to withstand, and means of intra and inter-shot control are under investigation Select castellations in divertor regions will be instrumented with thermocouples designed to measure the shot-integrated energy deposited in each castellation. The thermocouples are located away ~25mm from the plasma facing surface to prevent stress concentrations in the castellations. The deposited energy is therefore determined by finite element analysis of the thermal behavior of the tile consistent with the thermal wave propagation in the castellations. We present experimental testing and validation of a castellated graphite target instrumented with thermocouples at various depths in the castellation. During testing, incident heat flux is provided by a programmed, electron beam system and surface temperatures are measured via infrared thermography directly viewing the target surface.

Speaker: Travis Gray (ORNL)
• 16:01
8.30 First time-resolved electron density measurements in the C-2W Advanced Field Reversed Configuration plasmas from long-path compact second-harmonic interferometer 2h

Characterization of plasma structure and density is critical for diagnosis and control of C-2W plasma equilibria. To this end, two compact, highly portable, turnkey second harmonic interferometers[1] are used to make measurements with greater flexibility than available from other diagnostics, providing important information sooner than what would be possible from more complicated systems and in areas otherwise inaccessible. The systems are based on a fiber-coupled 1064nm Nd:YAG laser, and provide a sensitivity of a few 1019 m-2 with a time resolution of a few microseconds. System upgrades were made to allow for beam paths in excess of five meters. Data from two system configurations will be presented, showing plasma translation and merged equilibria.
[1] F. Brandi, et al., Rev. Sci. Instrum., 80, 113501 (2009)

Speakers: Michael Beall (TAE Technologies, Inc.), Daniel Sheftman (TAE Technologies, Inc.), The TAE Team
• 16:01
8.31 A Divertor Scraper Observation System for Wendelstein 7-X 2h

A graphite element, called a scraper [1], will be installed in 2018 on the Wendelstein 7-X stellarator in the throat of the divertor (at two out of ten potential toroidal locations). We have designed, built, and calibrated a new infrared/visible imaging endoscope system to enable detailed observations of the plasma interactions and heat loads at one of the scrapers, and the neighboring divertor surfaces. The new endoscope uses a shuttered, pinhole-protected, pair of 90° off-axis 218 mm focal length aluminum parabolic mirrors in vacuum, and two flat turning metal mirrors, to send light to a sapphire window 1.4 meters away, beyond which we have co-located telephoto lens-based mid-infrared and visible cameras. The camera field of view covers the entire 650 mm length of the scraper, and includes locations monitored by thermocouples and Langmuir probes embedded in some of the scraper tiles. Detailed design, assembly tests, installation, and comparison of predicted (ZEMAX) and actual optical test performance will be discussed.
[1] A. Lumsdaine, et al., IEEE Transactions on Plasma Science (Volume: 44, Issue: 9, pg. 1738-1744, Sept. 2016 )

Speakers: Glen Wurden (Los Alamos National Laboratory), Joris Fellinger (Max Planck Institute for Plasma Physics), Peter Drewelow (Max Planck Institute for Plasma Physics), Oliver Ford (Max Planck Institute for Plasma Physics), Marc Gamradt (Max Planck Institute for Plasma Physics), Henry Greve (Max Planck Institute for Plasma Physics), Marcin Jakubowski (Max Planck Institute for Plasma Physics), Hartmut Jenzsch (Max Planck Institute for Plasma Physics), Holger Niemann (Max Planck Institute for Plasma Physics), Aleix Puig Sitjes (Max Planck Institute for Plasma Physics), The W7-X Team (Max Planck Institute for Plasma Physics)
• 16:01
8.32 Calibration and applications of imaging diagnostics on the C-2U advanced beam-driven field-reversed configuration device 2h

Two filtered fast-imaging instruments, with radial and axial views, respectively, were used on the C-2U device to visualize line emission from impurities and hydrogenic neutrals. Due to the accelerated pace of C-2U operations, in-vessel access was not available; as a result, novel calibration techniques needed to be developed. Spatial calibration involved optimizing parameters in a generic camera model: ex-situ using a checkerboard target and in-situ using the vacuum vessel port geometry. Photometric calibration was performed ex-situ in three stages. First, the camera relative response function was mapped using an algorithm developed for high dynamic-range imaging. Second, the non-uniformity of the optical system was measured using a large LCD monitor with known angular emission pattern. Finally, the absolute photon efficiency of each interference filter was determined using a calibrated uniform radiance source. Drift of the photometric calibration was tracked in-situ by measuring line emission from neutral beams fired into a gas target. One application using calibrated camera data was tomographic reconstruction of emissivity from O 4+ . This emissivity provided a sanity check with the excluded-flux radius inferred from wall-mounted magnetic sensors.

Speakers: Erik Granstedt (TAE Technologies, Inc.), D. Fallah (TAE Technologies, Inc.), M. Thompson (TAE Technologies, Inc.), The TAE Team
• 16:01
8.33 Signal-to-background ratio of a Thin foil Proton Recoil neutron spectrometer at ITER 2h

The Thin foil Proton Recoil spectrometer (TPR) concept has previously been used at JET as a DT fusion neutron diagnostic. It is also one of the techniques suggested for use at ITER as part of the high resolution neutron spectrometer system. The main purpose of the neutron spectrometers at ITER is to determine the fuel ion density ratio in DT plasmas. The TPR principle is based on the detection of recoil protons produced due to (n,p) elastic neutron scattering in a thin CH foil. Some of the produced protons will interact in a dedicated detector. For the suggested high resolution neutron spectrometer system at ITER, the TPR proton detector is based on the dE-E principle. In this study, the dE-E capability of a silicon detector system has been experimentally investigated using mono-energetic proton beams. The measurement was conducted at the Uppsala University TANDEM accelerator using proton beam energies of 3 – 8 MeV for proof of concept. The experimentally obtained results together with Monte-Carlo background simulations are used to estimate the expected signal-to-background ratio for a TPR system during DT operations in ITER.

Speakers: Benjaminas Marcinkevicius (Uppsala University), Anders Hjalmarsson (Uppsala University), Erik Andersson Sundén (Uppsala University), Göran Ericsson (Uppsala University)
• 16:01
8.34 Characterization of Biermann-Battery field advection in NIF cylindrical geometry targets 2h

Lasers incident on solid targets produce B-fields around the laser spot due to orthogonal ne and Te gradients that develop near the target surface[1]. Simulations show that these fields are produced in hohlraum experiments at the NIF[2], and that the presence of B-fields can affect particle and energy transport. Little work exists comparing simulated fields predicted by MHD models to data at scales relevant for NIF hohlraum experiments (~10 ns, ~few mm)[3]. In particular, the relative contributions of frozen-in and Nernst advection of the field away from the hohlraum wall is not well understood. We have developed a new target platform for measuring B-field topology in a NIF-relevant geometry. Using NIF outer cones, a 2.5 mm long, 5.4 mm diameter Au ring is illuminated with a similar beam pattern to that of a ring of beams in a hohlraum. This provides a clear line of sight for probing through the ring by protons from an imploded D3He-filled capsule 2.5 cm below the ring. Proton deflection is recorded on CR39, allowing estimates of E- and B-field strength and topology in the target and contributions from different advection mechanisms. This work performed under auspices of US DOE by LLNL under Contract DE-AC52-07NA27344 with LDRD support.
[1] Stamper PRL
[2] Farmer PoP
[3] Li Science

Speakers: Bradley Pollock (LLNL), Alastair Moore (LLNL), Nathan Meezan (LLNL), Jave Kane (LLNL), David Strozzi (LLNL), Scott Wilks (LLNL), Darwin Ho (LLNL), Grant Logan (LLNL), William Farmer (LLNL), Mordecai Rosen (LLNL), Mark Herrmann (LLNL), John Moody (LLNL)
• 16:01
8.35 Initial Deployment of a Spatial Heterodyne Spectrometer to Measure Local Electric and Magnetic Field Fluctuations at DIII-D 2h

Local measurements of electrostatic and magnetic turbulence (~E and ~B) in fusion grade plasmas are a critical missing component in advancing our understanding of turbulent transport. A novel diagnostic for measuring these fluctuations is being developed. It employs high-speed measurements of the spectral linewidth of the Motional Stark Effect split neutral beam emission, where the amount of splitting is proportional to local magnetic and electric fields at the emission site. A spatial heterodyne spectroscopy (SHS) technique with high spectral resolution (~0.025 nm), high throughput (~0.02 cm^2 sr), and high speed (f ~ 250 kHz) is used as the MSE spectrum analyzer. A prototype SHS has been deployed to D3D for initial testing in the tokamak environment. A major contributor to loss of fringe contrast and thus SNR is line broadening arising from employing a large etendue collection lens. This is solved by making the collection optic conjugate with the image field containing the interference fringes via a small relay lens system and then tilting the gratings in the SHS. The change in effective groove density with tilt angle imposes a spatial shift in wavelength equal and opposite to that produced by the collection optic. Work supported by US DOE grant DE-FG02-89ER53296.

Speakers: Marcus G. Burke (University of Wisconsin - Madison), Raymond Fonck (University of Wisconsin - Madison), George Mckee (University of Wisconsin - Madison), Greg Winz (University of Wisconsin - Madison)
• 16:01
8.36 Magnetic Diagnostic Suite of the C-2W Field-Reversed Configuration Experiment 2h

A fundamental component of any magnetically confined fusion experiment is a firm understanding of the magnetic field. The increased complexity of the C-2W machine warrants an equally enhanced diagnostic capability. C-2W is outfitted with over 700 magnetic field probes of various types. They are both internal and external to the vacuum vessel. Inside, a linear array of innovative in-vacuum annular flux loop / B-dot combination probes provide information about plasma shape, size, pressure, energy, temperature, and trapped flux when coupled with establish theoretical interpretations. A linear array of B-dot probes complement the azimuthally averaged measurements. A Mirnov array of 64 3D probes, with both low and high frequency resolution, detail plasma motion and MHD modal content via singular value decomposition analysis. Internal Rogowski probes measure axial currents flowing in the plasma jet. Outside, every feed-thru for an internal probe has an external axial field probe. There are many external loops that measure the plasma formation dynamics and the total external magnetic flux. The external measurements are primarily used to characterize eddy currents in the vessel during a plasma shot. Details of these probes and the data derived from their signals will be presented.

Speakers: T. Roche (TAE Technologies, Inc.), M. C. Thompson (TAE Technologies, Inc.), M. Griswold (TAE Technologies, Inc.), K. Knapp (TAE Technologies, Inc.), B. Koop (TAE Technologies, Inc.), A. Ottaviano (TAE Technologies, Inc.), M. Tobin (TAE Technologies, Inc.), The TAE Team
• 16:01
8.37 Measuring non-axisymmetric fields from internal and external sources in the DIII-D tokamak* 2h

The magnetic field on a closed surface can be uniquely decomposed into contributions from currents internal and external to the surface [A.H. Boozer, Nucl. Fusion 55, 025001 (2015)]. In the context of a magnetic fusion device, this general principle implies that given a sufficient set of magnetic diagnostics just outside the plasma surface, the plasma’s contribution to the magnetic field can be distinguished from that of external currents – without the need for a specific model of either the plasma or the external currents. For example, this principle enables a direct measurement of the field of a growing plasma instability, without the need for a model of the currents that it induces in the resistive vessel wall. Similarly, it allows a direct measurement of the stable plasma response to an external magnetic perturbation, separate from the field of the external coils that impose the perturbation. We will discuss the requirements on magnetic diagnostics for such measurements. Applications of the technique to measurements in the DIII-D tokamak will be shown, including the case of a rotating tearing mode as it becomes locked to the wall.
*Work supported by US DOE under DE-FC02-04ER54698.

Speakers: Edward Strait (General Atomics), Ryan Sweeney (ITER Organization)
• 16:01
8.38 FIDA Diagnostic Development for the C-2W Field-Reversed Configuration Plasma 2h

"TAE’s advanced, beam-driven field-reversed configuration device has a large fast-ion population, allowing for fast-ion D-alpha (FIDA) studies. Development of a FIDA spectrometer for the new C-2W device is underway. Previous measurements [1] were combined with C-2W geometry to inform the design. Measured signal levels led to the purchase of a Phantom Miro 110 high-speed camera that will be paired with Kaiser’s Holospec f/1.8 spectrograph. The spectrograph utilizes a custom transmission grating centered at 656.0 nm. Simulations were used to choose available ports with expectedly large signals. Eight neutral beams and 354 ports were considered. Experimentally-obtained 1D plasma profiles from C-2U were mapped onto Q2D [2] simulation flux surfaces. For each point on the vessel wall, many lines-of-sight (LOS) are created to view the entirety of each neutral beam path. FIDA spectra are simulated for each LOS using FIDASIM [3]. Integrating over wavelength and beam-space allows individual ports to be chosen for their large prospective signals.
1. Rev. Sci. Instrum. 87, 11E520 (2016)
2. Physics of Plasmas 24, 092518 (2017)
3. http://d3denergetic.github.io/FIDASIM/index.html"

Speakers: Nathan Bolte (TAE Technologies, Inc. ), Marcel Nations (TAE Technologies, Inc. ), Deepak Gupta (TAE Technologies, Inc. )
• 16:01
8.39 Characterizing the modulation transfer function for X-ray radiography for HED experiments 2h

X-ray radiography is a powerful tool for diagnosing high energy density states. In particular, face-on X-ray radiography is used in material strength experiments on the NIF. In these experiments, Rayleigh-Taylor (RT) growth is monitored in samples with pre-formed ripples driven to high pressure with the departure from classical RT growth attributed to material strength. In this experiment, the ability to resolve the opacity contrast between peaks and valleys of the RT growth is critical for accurate determination of the growth factor. Here we study the effect of polychromaticity of the backlighter and a large spatial extent of the source due to high-energy x-ray transmission. The performance of these measurements can in part be characterized by the modulation transfer function (MTF), which is estimated using the knife-edge technique. We present results from recent experiments using the NIF.
*This work was performed under the auspices of the Lawrence Livermore National Security, LLC, (LLNS) under Contract No. DE-AC52-07NA27344.

Speakers: Hye-Sook Park (LLNL), A. Krygier (LLNL), C. M. Huntington (LLNL), J. M. McNaney (LLNL), E. Gumbrell (AWE)
• 16:01
8.40 Experimental Tests of an Infrared Video Bolometer on Alcator C-Mod 2h

A prototype of an infrared imaging bolometer (IRVB) was successfully deployed and tested on the Alcator C-Mod tokamk during the end of the FY16 campaign. The IRVB method interprets the power radiated from the plasma by measuring the temperature rise of a thin, 2.5 micron Pt absorber that is exposed, through a pinhole aperture, to the full-spectrum of plasma photon emission. The IRVB was installed on C-Mod with a view of the poloidal cross-section of the core plasma. The temperature of the absorber was measured using a Cedip Titanium 550M camera with spectral response from 3.6-5.1 microns and framing rates up to 1 kHz for an image size of 256 x 64 pixels. Measurements taken over two run days (~50 discharges) included Ohmic and ICRF-heated H-mode and I-mode plasmas. Raw signal-to-noise ratios of ~100 were achieved. Initial quantitative comparisons of total radiated power and on-axis emissivity from IRVB are compared to results from resistive bolometers and AXUV-diodes. This IRVB is shown to be immune to electromagnetic interference from ICRF, which strongly impacts resistive bolometers, but sensitive to mechanical oscillations between the camera and absorber. Results of the benchtop calibration are summarized, showing noise equivalent power and frequency response.

Speakers: Reinke Matthew (Oak Ridge National Laboratory), James Terry (MIT Plasma Science and Fusion Center ), Stein van Eden (Dutch Institute for Fundamental Energy Research ), Byron Peterson (National Institutes for Quantum and Radiological Science and Technology), Kiyofumi Mukai (National Institutes for Quantum and Radiological Science and Technology), Travis Gray (Oak Ridge National Laboratory), Brent Stratton (Princeton Plasma Physics Laboratory)
• 16:01
8.41 The Engineering Challenges And Options For Fielding The Next Generation Gas Cherenkov Detectors At The National Ignition Facility 2h

Fielding the 3rd Generation Gas Cherenkov Detector (GCD3) onto the National Ignition Facility (NIF) encompassed commissioning of the WellDIM3.9m Insertion Manipulator at Port 64-275 of the NIF Target Chamber. Phase II enhancements include the integration of the Sydor/Kentech/Photek Pulse-Dilation Photomultiplier Tube (PD-PMT) onto the existing detector. Given the 10x measurement bandwidth improvement that the PD-PMT will provide, the next logical enhancement (Phase III) is to increase the detector’s sensitivity, i.e., position the detector closer to the Target Chamber Center. Concept options include: a.) Deploying the existing GCD3/PD-PMT Detector on the Target and Diagnostic Manipulator (TANDM), b.) Develop an optimized multi-cell Gas Cherenkov Detector (“Super-GCD”) also TANDM-based, or c.) Develop an integral Super GCD/Neutron Imaging System diagnostic for TANDM. This poster/paper highlights the engineering design challenges, methodologies, and possible solutions to achieving this goal. LA-UR-18-20260

Speakers: Frank Lopez (Los Alamos National Laboratory), H.W. Herrmann (Los Alamos National Laboratory), B.J. Pederson (Los Alamos National Laboratory), B.C. Steinfeld (Los Alamos National Laboratory), P.J. Polk (Los Alamos National Laboratory), J.L. Kline (Los Alamos National Laboratory), J.A. Oertel (Los Alamos National Laboratory), Y.H. Kim (Los Alamos National Laboratory), A.B. Zylstra (Los Alamos National Laboratory), K.D. Meaney (Los Alamos National Laboratory), H. Geppert-Kleinrath (Los Alamos National Laboratory), R.L. Hibbard (Lawrence Livermore National Laboratory), J.E. Hernandez (Lawrence Livermore National Laboratory), J.A. Carrera (Lawrence Livermore National Laboratory), H.Y. Khater (Lawrence Livermore National Laboratory), S. Sitaraman (Lawrence Livermore National Laboratory), C.J. Horsfield (Atomic Weapons Establishment), M.S. Rubery (Atomic Weapons Establishment), S. Gales (Atomic Weapons Establishment), A. Leatherland (Atomic Weapons Establishment), T. Hilsabeck (General Atomics), J.D. Kilkenny (General Atomics), R.M. Malone (National Security Technologies), J.D. Hares, A.K.L. Dymoke-Bradshaw (Kentech Instruments Limited), J. Milnes (Kentech Instruments Limited)
• 16:01
8.42 Measurements of Formation Dynamics in a Multi-Pulse Compact Toroid Injector System 2h

The C-2W experiment at TAE Technologies aims at sustaining an advanced beam-driven field reversed configuration (FRC) plasma. However, FRC lifetime is limited by particle confinement, among other factors. Injecting a supersonic compact toroid (CT) through the separatrix radius (Rs) is a means of refueling the FRC’s core with deuterium. For long-lived plasmas there is a need for multiple, non-disruptive, refueling events with uniform CTs. To develop a consistent and repetitive injection system a dedicated test bed exists to study formation dynamics, as well as translation and merging of CTs. The test bed is outfitted with a diagnostic suite including b-dot probes, a triple probe, an interferometer, rogowskis and a collimated fiber optic array to measure plasma parameters such as electron density (ne), electron temperature (Te) and magnetic fields, in addition to macroscopic attributes such as CT velocity, volume and particle count. Neutral gas build-up has been mitigated, in part, by the adoption of a plasma source for pre-ionization which assists the compact toroid injector (CTI) breakdown and increases the ionization fraction. Particulars of pulse to pulse repeatability, which is affected by the accumulation of neutral gas, lingering plasma and pulsed power supply variation.

Speakers: Ian Allfrey (TAE Technologies, Inc.), Tadafumi Matsumoto (TAE Technologies, Inc.), Thomas Roche (TAE Technologies, Inc.), Hiroshi Gota (TAE Technologies, Inc.), Eusebio Garate (TAE Technologies, Inc.), The TAE Team
• 16:01
8.43 Real-time Dispersion Interferometry for Density Feedback in Fusion Devices 2h

Interferometry as one of the most common core fusion diagnostics has traditionally suffered from incomplete vibration compensation. Dispersion interferometry promises a more complete compensation of vibrations. For this reason it is being employed in an increasing number of experiments. However, thus far none of them have shown reliable real-time low-latency processing of dispersion interferometry data. Nonetheless this is a necessity for most machines when trying to do density feedback control, most notably in long discharges like the ones planned at the W7-X stellarator and ITER. In this paper we report the development of a new phase extraction method specifically developed for real-time evaluation using FPGAs. It has been shown to operate reliably during the OP1.2a operation phase at W7-X and is now routinely being used by the W7-X density feedback system up to very high densities above 1.4e20 1/m² without 2π-wraps. During the development of the method new insights into the signal composition of a dispersion interferometer have been gained leading to a new signal calibration relevant to other phase evaluation methods.

Speakers: Kai Jakob Brunner (Max-Planck-Institut for Plasma Physics, Greifswald), Akiyama Akiyama (National Institute for Fusion Science), Matthias Hirsch (Max-Planck-Institut for Plasma Physics, Greifswald), Jens Knauer (Max-Planck-Institut for Plasma Physics, Greifswald), Petra Kornejew (Max-Planck-Institut for Plasma Physics, Greifswald), Beate Kursinski (Max-Planck-Institut for Plasma Physics, Greifswald), Heike Laqua (Max-Planck-Institut for Plasma Physics, Greifswald), Jens Meinicke (Max-Planck-Institut for Plasma Physics, Greifswald), Humberto Trimino-Mora (Max-Planck-Institut for Plasma Physics, Greifswald), Robert C. Wolf (Max-Planck-Institut for Plasma Physics, Greifswald)
• 16:01
8.44 Micro Ion Spectrometer for Fusion Plasma Boundary Measurements 2h

As magnetically confined plasmas progress towards ignition and very long pulse experiments, the physics of the pedestal and diverter regions has become increasingly important. In particular, measurements of the ions in the scrape-off layer are needed. The energy spectra of the ions determines the rates of sputtering and erosion of the plasma facing surfaces. The ion spectra in the edge are not easily determined spectroscopically and must be measured in situ since the ions are confined by the strong magnetic fields of the tokamak. Conventional energy analyzers are too large and expensive to install in multiple locations around the torus. Thus, we are developing in situ probes to make direct, spatially resolved measurements of the ion energy spectra in the edge of tokamak plasmas that are easily replaced and require minimal resources. The probes are compact, low cost, and small enough to be placed inside of specially prepared wall tiles – essentially creating a “smart” plasma facing surface in a tokamak. Details of the prototype micro ion spectrometer and initial tests will be presented. Work supported by US DOE

Speakers: Amy Keesee (West Virginia University), Earl Scime (West Virginia University), Steve Ellison (Advanced Research Corporation), Joe Tersteeg (Advanced Research Corporation), Matt Dugas (Advanced Research Corporation)
• 16:01
8.45 Motional Stark effect imaging first results on DIII-D 2h

A motional Stark effect (MSE) imaging diagnostic was benchmarked against existing conventional MSE polarimeters on DIII-D and delivered new capabilities for measuring the magnetic pitch angle from 2 neutral beams and on the low field side of DIII-D. For 30 years conventional photoelastic modulator polarimeters have been used for constraining the toroidal current profile in fusion devices, however these systems require individual narrowband filters to track the Doppler shift of each channel and are therefore limited to 10s of channels. A more recently developed MSE technique utilises birefringent crystals to establish a sinusoidal spectral filter of period comparable to the pi-sigma splitting to allow imaging of the entire neutral beam emission without requiring to track the Doppler shift. While close agreement between the conventional and imaging systems is obtained for shots with toroidal magnetic field and plasma current in the normal direction, the consistency is lost for shots with either reversed field or current. An analysis of the magnetic axis position independently measured with the conventional MSE, imaging MSE, ECE and magnetics is presented to elucidate differences between the MSE measurements. *Work supported by U.S. DOE under DE-FC02-04ER54698 and DE-AC52-07NA27344

Speakers: Alex Thorman (Australian National University), Clive Michael (Australian National University), John Howard (Australian National University), Brian Victor (Lawrence Livermore National Laboratory), Chris Holcomb (Lawrence Livermore National Laboratory), Steve Allen (Lawrence Livermore National Laboratory)
• 16:01
8.46 Solid State Streak Camera Prototype Electronic Performance Testing and Improvements to Dynamic Range 2h

Streak Cameras are an essential diagnostic tool used in shock physics and high energy density physics experiments. Such experiments require well calibrated temporally resolving diagnostics for studying events that occur on the nanosecond to microsecond time scales. The Nevada National Security Site (NNSS) and Sandia National Laboratories (SNL) have built a 42-channel solid state streak camera (SSSC) prototype as a proof of concept for use as a streak camera replacement. This work is part of an ongoing project to develop the technology to a level competitive with analog streak cameras. The device concept, results from electronic testing and recent improvements to increase the device’s dynamic range will be discussed in this poster. DOE/NV/03624--0023

Speakers: Yekaterina Opachich (Nevada National Security Site), Lawrence MacNeil (Nevada National Security Site), John Porter (Sandia National Laboratory), James Heinmiller (Nevada National Security Site), Alarie Alicia (Nevada National Security Site), Mark Kimmel (Sandia National Laboratory), Joel Long (Sandia National Laboratory), Looker Quinn (Sandia National Laboratory), Don Max (Nevada National Security Site), John Stahoviak (Sandia National Laboratory), Thomas Waltman (Nevada National Security Site)
• 16:01
8.47 Upgrades to Thomson Scattering Detectors at General Fusion 2h

General Fusion is assembling an upgraded Thomson scattering system in preparation for measurements on the new PI3 plasma injector. Major changes include a shift of laser wavelength from 532 nm to 1064 nm and switching from a spectrometer and photomultiplier detector setup to polychromator and avalanche photodiode (APD) detector setup. A novel, inexpensive, tunable polychromator design will be tested. A comparison will be made between a variety of custom and off the shelf APD modules. Previously, a 532 nm based system was used with five chords on the smaller SPECTOR machine, measuring temperature and density of plasmas ranging over 50-400 eV and 0.3-1x1020 m-3. After initial testing, the new system will be expanded to eight modular chords.

Speaker: Young William (General Fusion)
• 16:01
8.48 Design of a CR-39 Based Compact DD Neutron Spectrometer for Measuring Yield, Ion Temperature, and Areal Density on the Z 2h

A compact neutron spectrometer, based on a CH foil for production of recoil protons and CR-39 detection, is being developed for measurements of DD-neutron spectra at Z. To accurately measure the DD ion temperature (Tion) of ~2 keV, the spectrometer must have an energy resolution (FWHM) of ~120 keV. Spectral broadening is primarily dominated by the finite thickness of the converter foil and track-diameter variations in the CR-39. To infer an areal density (ρR) background levels from neutron induced tracks need to be sufficiently low to measure the down scattered DD neutrons. This is done through a combination of shielding and the Coincidence Counting Technique (CCT) [1]. The spectrum itself is inferred from the track diameter distribution measured on the CR-39 detector. To this end, a novel analysis technique has been developed for determining the energy-diameter relationship required to recover the spectrum. Initial data from a crude prototype spectrometer has been collected from a few MagLIF shots at the Z facility. This work is supported by Sandia under DOE contract DE-NA0003525.
1) D. T. Casey et al. RSI 82, 073502 (2011)

Speakers: Brandon Lahmann (MIT Plasma Science and Fusion Center), Maria Gatu-Johnson (MIT Plasma Science and Fusion Center), Johan Frenje (MIT Plasma Science and Fusion Center), Fredrick Seguin (MIT Plasma Science and Fusion Center), Richard Petrasso (MIT Plasma Science and Fusion Center), Kelly Hahn (Sandia National Laboratories), Brent Jones (Sandia National Laboratories)
• 16:01
8.49 High Resolution Magnetic Field Measurements in Hydrogen and Helium Plasmas using Active Laser Spectroscopy 2h

Passive spectroscopic measurements of Zeeman splitting has been reliably used to measure magnetic fields in plasmas for decades. However, a requirement is that the field must be high enough to be resolved over Doppler and instrument broadening (typically >1 T). A synthetic diagnostic capable of measuring low magnetic fields (<5 mT) with high sensitivity (+/- 0.5 mT) is currently under development at Oak Ridge National Laboratory. The diagnostic relies on Doppler-free saturation spectroscopy (DFSS), an active, laser-based technique that greatly reduces Doppler and instrument broadening. To date, diagnostic has been successfully employed to measure the magnetic field in a magnetized (55-90 mT), low-temperature (5-20 eV), low-density (5e16-3e18 m^-3), hydrogen and helium plasma in the 5-200 mTorr pressure range using a low power (25 mW) diode laser. These measurements are presented and shown to be accurate within 0.5 mT. Crossover resonances (CR’s) (an artifact of the diagnostic) are also observed within the measured spectra. Parametric response of the CR’s to the magnetic field and gas temperature will be presented. A quantitative model, developed from these measurements, to accurately predict the CR’s behavior will also be given.

Speakers: Abdullah Zafar (North Carolina State University), Elijah Martin (Oak Ridge National Laboratory), Steve Shannon (North Carolina State University)
• 16:01
8.50 High-energy differential-filtering photon spectrometer for ultraintense laser-matter interactions 2h

The detection of x-rays in the 100s of keV to MeV range for picosecond laser-matter interactions provides understanding of the laser to relativistic electron coupling, which is critical for applications such as Compton radiography, positron-electron pair production, and TNSA proton generation. Spectroscopy in the range of 0.1-2 MeV is difficult due to the high photon flux for single counting devices; while at such energies, the photons have low interaction cross sections with crystals and Cherenkov detectors. Here, we describe a novel geometry of a step filter to measure high energy bremsstrahlung emission for positron-electron pair production experiments. The design allows for independent determination of a local background noise that reduces the systematic error in the reconstructed spectra. Bremsstrahlung emission was measured for various laser and target conditions and correlated to pair production yields. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344 and funded by the LLNL LDRD program under tracking code 17-ERD-010.

Speakers: Jackson Williams (LLNL), Riccardo Tommasini (LLNL), Brian Ryba (UC San Diego), Hui Chen (LLNL)
• 16:01
8.51 Impact of Response Function Uncertainty and Gamma Backgrounds on Measurements from Cerenkov Detectors at the National Ignition Facility (NIF)* 2h

The instrument response function of neutron time-of-flight (nToF) systems is a major contributor to both systematic and statistical uncertainties of derived quantities of interest. In particular, the first and second moments of these distributions are associated with arrival time, t0, and ion temperature Tion. Response times of Cerenkov radiators recently deployed at NIF are set by neutron transit times across the detector, rather than long response-time tails characteristic of scintillation detectors. We present the results of uncertainty analysis showing the significant reduction of uncertainty in determining these quantities using the Cerenkov detector system recently deployed at NIF. The increased sensitivity to gamma radiation requires additional consideration of the effect of this background to the uncertainties in both t0 and Tion. Leveraging the well-understood nature of the Cerenkov process, high fidelity Monte Carlo simulations are combined with analysis techniques to evaluate the effect of background on measured NIF spectra. *Work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under contract DE-AC52-07NA27344.

Speakers: Edward Hartouni (Lawrence Livermore National Laboratory), Bart Beeman (Lawrence Livermore National Laboratory), Mark Eckart (Lawrence Livermore National Laboratory), Gary Grim (Lawrence Livermore National Laboratory), Robert Hatarik (Lawrence Livermore National Laboratory), Alastair Moore, Michael Rubery (Lawrence Livermore National Laboratory), Daniel Sayre (Lawrence Livermore National Laboratory), David Schlossberg (Lawrence Livermore National Laboratory), Cory Waltz (Lawrence Livermore National Laboratory)
• 16:01
8.52 Electron-lattice coupling in femtosecond laser excited matter 2h

Electron-lattice coupling strength governs the energy transfer between electrons and lattices and is important for understanding the material behavior under thermal non-equilibrium conditions. Here we employed time-resolved electron diffraction at MeV energies to directly study the electron-lattice relaxation in 40-nm-thick polycrystalline copper excited by femtosecond optical lasers. The temporal evolution of lattice temperature over a range of excitation fluences were obtained from the measurements of Debye-Waller decay of multiple diffraction peaks. The lattice temperature results were compared to two-temperature model simulations to derive the electron-lattice coupling strength in copper. This work was supported by the U.S. DOE Office of Science, Fusion Energy Science under FWP #100182.

Speakers: Mianzhen Mo (SLAC National Accelerator Laboratory), Valerie Becker (Department of Physics, Southern Illinois University Edwardsville), Benjamin Kwasi Ofori-Okai (SLAC National Accelerator Laboratory), Zhijiang Chen (SLAC National Accelerator Laboratory), Bastian Witte (SLAC National Accelerator Laboratory), Xiaozhe Shen (SLAC National Accelerator Laboratory), Renkai Li (SLAC National Accelerator Laboratory), Xijie Wang (SLAC National Accelerator Laboratory), Siegfried Glenzer (SLAC National Accelerator Laboratory)
• 16:01
8.53 Development of O mode multichannel correlation reflectometry on EAST tokamak 2h

In order to effectively carry out the research of Plasma turbulence，a multichannel correlation reflectometry has been developed on EAST tokamak , which working in the frequency range of (20GHz-60GHz) and with the polarization of ordinary mode. The system can probe eight different radial locations simultaneously by launching eight fixed frequencies (20.4GHz,24.8GHz,33GHz,40GHz 42.5GHz,48GHz,52.6GHz, 57.2GHz) and also two different poloidal position simultaneously through two poloidal separated receive antenna. The set up enables the measurement of density fluctuation cover the area from pedestal to core plasma in the routine plasma operation on EAST. In this article, the hardware design and the laboratory test and also the preliminary experimental results on the EAST will be presented .

Speakers: Haoming Xiang (University of Science and Technology of China), Fei Wen (Institute of Plasma Physics, Chinese Academy of Sciences), Tao Zhang (Institute of Plasma Physics, Chinese Academy of Sciences)
• 16:01
8.54 Development of a multi-channel capacitive probe for electric field measurements with fine spatial resolution 2h

Reliable electric field measurements in a plasma are challenging, especially when fine resolution of spatial structure is critical. A capacitive probe [Mingsheng, Tan, et al. Rev. Sci. Instrum 88, 023502 (2017)] is one of a few diagnostics that are directly sensitive to the plasma potential. In such a probe, a boron nitride ceramic (BN) covers an electrode and a capacitor is formed between the electrode and the plasma with the BN serving as a dielectric material. When the electron temperature is above 18 eV, the floating potential of the BN becomes the same as the plasma potential due to increased secondary electron emission. Therefore, the spatial structure of the electric field can be measured by using an array of capacitive electrodes. We develop a multi-channel capacitive probe for fine radial electric field measurements. In order to assure stable operation of an electrode with small collecting surface area over a wide frequency range, a high input impedance amplifier with driven guard is employed. Preliminary data are presented showing that the multi-channel capacitive probe can resolve both equilibrium, few hundreds of Hz, and fluctuating, up to ~500 kHz, radial electric fields with the spatial resolution of 7 mm.

• 16:01
8.55 Experimental comparison of spherically bent HAPG and Ge crystal 2h

The Orion high-resolution X-ray (OHREX) focusing, imaging spherically bent crystal spectrometer, operated with both image plates and CCD cameras, has been providing time-averaged plasma diagnostics through high-resolution spectroscopy with good signal-to-noise at the Orion Laser facility. For the next step towards time-resolved plasma diagnostics to be achieved by using the OHREX in conjunction with a streak camera, even higher signal rates are desirable. Using the OHREX's sister instrument, EBHiX, at the LLNL electron beam ion trap EBIT-I, we therefore compare the efficiency of a high-quality Ge (111) crystal ($2d=6.532$\,\AA{}) with that of a higher-reflectivity, but lower-resolution HAPG crystal ($2d=6.708$\,\AA{}) in the energy range 2408 to 2452 eV. We find that the HAPG provides overall more signal across the entire image, but, because of the much better focusing properties of the Ge crystal, the latter provides more signal within the central 100 um of the spatial profile in cross-dispersion direction and is thus more suitable for the narrow entrance window of the Livermore-built streak camera. This work was performed under the auspices of the U.S. DOE by LLNL nunder Contract No. DE-AC52-07NA27344.

Speakers: Natalie Hell (LLNL), Tom Lockard (LLNL), Peter Beiersdorfer (LLNL), Ed W. Magee (LLNL), Greg V. Brown (LLNL), Ronny Shepherd (LLNL), Thusitha Arthanayaka (LLNL & Columbia University)
• 16:01
8.56 Microwave frequency comb Doppler reflectometer applying fast digital data acquisition system in LHD 2h

As for studying the behavior of the turbulence affecting transport, the multi-scale turbulence interaction is receiving much attention at present. For this aim, higher spatial and temporal resolution diagnostics have been developed and applied in several devices [1]. In LHD, such the precise spatio-temporal behavior of turbulence flow velocity and intensity has been measured by the multi-channel microwave frequency comb Doppler reflectometer system [2, 3]. Recently, we succeeded in increasing the radial observation points of this Doppler reflectometer system up from 8 to 20 (or especially up to 60). The high sampling rate of 40 GS/s is utilized for the digital signal processing. The detail of the system and some topical results will be presented and the application technique will be discussed.
[1] T. Tokuzawa, Nuclear Fusion 57 (2017) 025001.
[2] T. Tokuzawa et al., Plasma Fusion Res. 9 (2014) 1402149.
[3] T. Tokuzawa et al., Phys. of Plasmas 21 (2014) 055904.
The present study was supported in part by KAKENHI (Nos. 17K18773, 17H01368, 15H02335, and 15H02336), by a budgetary Grant-in-Aid from the NIFS LHD project under the auspices of the NIFS Collaboration Research Program, and by Collaborative Research Program of RIAM of Kyushu University.

Speakers: Tokihiko Tokuzawa (National Institute for Fusion Science), Hayato Tsuchiya (National Institute for Fusion Science), Shigeru Inagaki (Kyushu University), Katsumi Ida (National Institute for Fusion Science), Hiroshi Yamada (National Institute for Fusion Science), Akira Ejiri (The University of Tokyo), Kiyomasa Watanabe (National Institute for Fusion Science), Kazuki Oguri (Nagoya University), Tsuyoshi Akiyama (National Institute for Fusion Science), Kenji Tanaka (National Institute for Fusion Science), Ichihiro Yamada (National Institute for Fusion Science), LHD Experiment Group (National Institute for Fusion Science)
• 18:00 21:00
Banquet: Banquet - Bus departure 6:15PM
• Wednesday, 18 April
• 07:00 08:15
Breakfast
• 08:30 10:30
Session #9, Wednesday Morning Invited Talks, Chair: T. Biewer
• 08:30
9.1 Tomographic Analysis of Complex Plasmas 30m

Many tokamaks now use visible light cameras to observe plasma-wall interactions and integrated line emission. The DIII-D Coherence Imaging Spectroscopy diagnostic cameras image interferograms that encode line integrated flow. By modeling the 2D camera image pixels as line-of-sight integrals through an axisymmetric discrete grid it is possible to do tomographic analysis to determine the local plasma line emissivity and parallel flow. We present methods to solve the inverse problem posed by these tangential viewing cameras. The inversion begins with calculation of the sparse response matrix that encompasses all the geometry and diagnostic information and reduces the process of image formation to a sparse matrix-vector multiply. This work includes techniques of determining the detailed geometry of the camera views and methods for handling physical quantities that vary spatially. Additionally, the size of the response matrix has driven the development of capability to distribute the coarse parallel calculation across a heterogeneous cluster of computers on the Energy Sciences Network. Iterative techniques are then used to solve the sparse matrix-vector linear system.Work performed by LLNL under auspices of US DOE, Contract No. DE- AC52-07NA27344 and DE-FC02-04ER54698.

Speakers: William Meyer (LLNL), Steven Allen (LLNL), Max Fenstermacher (LLNL), Cameron Samuell (LLNL)
• 09:00
9.2 Using Integrated Data Analysis to Extend Measurement Capability 30m

The analysis approach often called “integrated data analysis” (IDA) provides a means to exploit all information present in multiple streams of raw data to produce the best estimate of a plasma parameter. This contrasts with the typical approach in which information (data) from a single diagnostic is used to measure a given parameter, e.g., visible bremsstrahlung→Zeff or Thomson scattering (TS)→Te. Data from a given diagnostic usually contains information on many parameters. For example, a TS diagnostic is sensitive to bremsstrahlung and line emission in addition to Te. This “background” light is typically subtracted off, but can be used to improve knowledge of Zeff. IDA encourages explicit awareness of such information and provides the quantitative framework to exploit it. As an example, IDA enabled measurement of Zeff on MST, as no single diagnostic provided a robust measurement. As we enter the burning plasma era, application of IDA may be critical to measurement of certain parameters, as diagnostic access in the harsh fusion environment will be extremely limited. This material is based upon work supported by the U.S. Department of Energy Office of Science, Office of Fusion Energy Sciences program under Award Numbers DE-SC0015474 and DE-FC02-05ER54814.

Speaker: Lisa M. Reusch (Dept. of Physics, University of Wisconsin - Madison)
• 09:30
9.3 Multi-Objective data analysis using Bayesian Parameter Estimation for the Interpretation of Magnetized Liner Inertial Fusion experiments 30m

The Magnetized Liner Inertial Fusion (MagLIF) concept has recently demonstrated Gbar pressures, confinement of charged fusion products, and substantial fusion yield. We have developed a new analysis methodology that allows for the self-consistent integration of multiple diagnostics including nuclear, x-ray imaging, and x-ray power measurements to determine important stagnation parameters. The analysis uses a simplified model of the hotspot in conjunction with a Bayesian inference network to determine the most probable configuration that describes the experimental observations. The analysis is also used to reveal correlations in the data and model parameters as well as to assess the value of the diagnostics. We present the details of the model used as well as the results of validation tests. We demonstrate the method on experimental data and show how new diagnostics can be added or existing ones optimized to reduce uncertainties. *Sandia National Laboratories is a multimission laboratory managed and operated by National Technology and Engineering Solutions of Sandia, LLC., a wholly owned subsidiary of Honeywell International, Inc., for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-NA-0003525.

Speakers: Patrick Knapp (Sandia National Laboratories), Michael Glinsky (Sandia National Laboratories), Christopher Jennings (Sandia National Laboratories), Stephanie Hansen (Sandia National Laboratories), Matthew Evans (University of Rochester)
• 10:00
9.4 Simultaneous visualization of wall motion, drive beam propagation, and implosion symmetry by using hohlraums with thin-wall patches at the National Ignition Facility 30m

To achieve a symmetric implosion with indirect drive, it is crucial to understand the dynamic behavior of laser transport in the hohlraum. This is particularly important in targets with lower initial gas-fill density since the region of the hohlraum wall irradiated by the outer cone beams bulges into the gas and can impair the propagation of the inner cone beams. Similarly, material ablated off the capsule surface can absorb the inner cone laser power before it reaches the hohlraum wall where it is converted to x-ray drive. We have developed a thin-walled hohlraum target which we use in a series of experiments to characterize laser beam propagation and hohlraum wall motion. We observe the bulge of the hohlraum wall with an x-ray framing camera positioned on the hohlraum axis. Time dependent power delivery to the equator is observed as x-ray emission through a thin-wall patch on the hohlraum. The self-emission x-ray image of the imploded core shows the cumulative effect of the asymmetric drive up to the maximum x-ray emission time. By changing the hohlraum fill density, the drive pulse shape (strength of the picket) and the capsule size, we study how those conditions affect the power delivery and asymmetry of the implosion.

Speakers: Nobuhiko IZUMI ( LLNL), N. Meezan (LLNL), S. Johnson (LLNL), B. N. Woodworth (LLNL), O. Jones (LLNL), O.L. Landen (LLNL), J.J. Kroll (LLNL), S. Vonhof (LLNL), A. Nikroo (LLNL), J. Jaquez (General Atomics), C. Bailey (LLNL), M. Hardy (LLNL), R. Ehrlich (LLNL), J. Ralph (LLNL), R. Pj. Town (LLNL), D.K. Bradley (LLNL), D. E. Hinkel (LLNL), A. Moore (LLNL), L. Divol (LLNL), C. Young (LLNL), J. D. Moody (LLNL)
• 10:30 13:01
Session #10, Wednesday Morning Poster Session
• 10:30
10.1 Recent Developments and Near-term Plans for DIII-D Diagnostics 1h 30m

The DIII-D diagnostic set combines expansions of established systems with implementations of new technologies to improve measurement and associated model validation from the boundary to the core plasma. A recent addition of translatable in-vacuum mirrors controllably alters a laser path within the Thomson Scattering system to adapt to the divertor geometry of particular experiments. The resulting electron density and temperature measurements provide information concerning detachment in the divertor. A new system is the Imaging Neutral Particle Analyzer (INPA), which measures radial profiles of core energetic ion density over narrowly defined regions of velocity space to provide information concerning beam ion transport. Future developments include high-Z spectroscopy suited to transport of tungsten and molybdenum as injected following the commissioning of a Laser Blow Off system. Measurements of the neutral density profile will necessarily become a focus as different divertor geometries are investigated. As four (of eight) neutral beams become capable of off-axis injection, new measurement possibilities will be explored, including flow velocity and ion temperature determination with divertor charge exchange. This work is supported in part by US DOE under DE-FC02-04ER54698.

Speaker: David Pace (General Atomics)
• 10:30
10.2 Time-Resolved X-Ray Diagnosis Of Hydrodynamic Processes Of Radiation-Ablated Gold Plasma In An Elongated Diagnostic Hole 1h 30m

Diagnostic hole used in indirect-drive inertial confinement fusion cannot be too large to cause severe radiation loss and affect the radiation uniformity in the hohlraum, or too small in case the plasma filling would block diagnostic holes and affect the diagnosis. An elongated hole is chosen as an extreme case to study the plasma movement in diagnostic hole in order to provide reference for the diagnostic hole design. The elongated diagnostic hole on the gold hohlraum wall was 150 μm in diameter and 100 μm deep. The peak radiation temperature of hohlraum was about 180 eV. The hydrodynamic processes in the elongated hole was observed by an X-ray framing camera. Laser-irradiated Ti disk was used to generate 2-5 keV narrow energy X-ray as the intense backlighter source. The plasma areal density distribution and evolution in the elongated hole was quantitatively measured and can be used to assess the effect of hydrodynamic processes on the diagnosis from the diagnostic hole.

Speaker: Hang Li (Research Center of Laser Fusion, China Academy of Engineering Physics)
• 10:30
10.3 Effect of multi-ion source injection on motional Stark effect diagnostic 1h 30m

Many tokamak devices utilize high-power neutral beams for various beam-based active spectroscopic diagnostics such as motional Stark effect (MSE). For higher heating performance, it is customary for the neutral beam injection (NBI) to be made with a multiple number of ion sources, which often times conflicts the environment that the active spectroscopic systems desire. This is mainly because the atomic and molecular emissions taking place from the interactions with multiple beams, or from different flux surfaces, are collected through the front optics at the same time, resulting in systematic errors in the measured quantities. In this work, the effect of the multiple ion source injections on the pitch angle measurements by the MSE diagnostic is quantitatively studied based on both numerical modeling and measurements made from the plasma discharges for the Korea Superconducting Tokamak Advanced Research. The sensitivity of the pitch angle against various combinations of the acceleration voltages of the ion sources is evaluated, yielding the optimum configuration of the beam injection that can maximize the heating efficiency with an acceptable level of the systematic offset in the MSE measurements. This work is supported by the Ministry of Science and ICT in Korea.

Speaker: Jinseok Ko (National Fusion Research Institute)
• 10:30
10.4 Enhanced high-temperature microparticle tracking using machine learning 1h 30m

Material clusters of different sizes are known to exist in high-temperature plasmas due to plasma-wall interactions. The facts that these clusters, ranging from sub-microns to above mm in size, can move from one location to another quickly, and that there are a lot of them, make high-speed imaging and tracking one of the best, effective, and sometimes only diagnostic. A machine learning technique based on neural networks is developed to analyze high-speed videos of high-temperature micro-clusters generated from exploding wires. The neural network utilizes a locally competitive algorithm to generate and optimize a set of dictionaries containing kernels, or bases, for image analysis. Our primary goal is to use this method for feature recognition and prediction of the microparticle motion. Results from machine-generated kernels are compared with physically-motivated kernels, where hand-picked kernels are used in conjunction with machine-generated ones. Our work indicates that machine-learning and supervised machine learning techniques are promising approaches to process large sets of images for high-temperature plasmas and other scientific experiments. Machine learning techniques will be useful to aid the understanding of plasma-wall interaction.

Speaker: Bradley Wolfe (Los Alamos National Lab)
• 10:30
10.5 2D GEM based imaging detector development from perspective of high intensity soft X-ray plasma radiation 2h

The proposed work is devoted to design, construction and testing advanced imaging diagnostics that will be able to perform the global SXR imaging ultimately aimed at both high Z and light impurities tracking. The detection structure is based on triple GEM amplification structure followed by the pixel readout electrode. The efficiency of detecting unit was adjusted for the radiation region of tungsten in high-temperature plasma. It provides 2D imaging with high time resolution (sub millisecond), high sensitivity and signal to noise ratio, good energy discrimination, with ability to address and programme single pixels.This work will present the detector characteristics and preliminary laboratory results obtained for the developed system. The operational characteristics and conditions of the detector were designed to work in the X-Ray range of 2–17 keV. Stream-handling data acquisition mode was developed for the detecting system with timing down to the ADC sampling frequency rate (~13 ns). The spatial resolution and imaging properties of this detector were studied for conditions of high counting rates and high gain. Imaging capabilities of GEM detectors were tested with different patterned anode planes (i.e. different readouts) to verify the detector high rate capability.

Speaker: Maryna Chernyshova (IPPLM)
• 10:30
10.6 Edge toroidal rotation shear dependence of the H-mode power threshold on EAST tokamak 1h 30m

Understanding of the influence of the edge toroidal rotation on the L-H transition power threshold is important for improving the plasma performance of future fusion devices. An edge toroidal charge exchange recombination spectroscopy (eCXRS) diagnostic has been deployed recently on the Experimental Advanced Superconducting Tokamak (EAST), providing the edge toroidal rotation. Experimental investigations on EAST show that the L-H transition power threshold depends approximately on the edge toroidal rotation by eCXRS. Generally, the threshold power increases with the increasing edge toroidal rotation for both normal Bt and reversal Bt plasmas. However, this result is not applicable in all cases.A new criterion has been founded that the L-H transition power threshold depends strongly on the edge toroidal rotation shear. L-mode shots and L-H transition shots also have obviously different edge rotation shear in the figure 2. The observed reduction of power threshold with decreasing rotation shear could be explained by the change of edge radial electric field structure, induced by rotation shape. This reduced power threshold at lower toroidal rotation and lower rotation shear could benefit to inherently low-rotation plasma such as ITER and CFETR.

Speaker: Di Jiang (University of Science and Technology of China )
• 10:30
10.7 Measurement of bremsstrahlung radiation from runaway electrons with the Gamma Ray Imager on DIII-D 1h 30m

The Gamma Ray Imager (GRI) is a novel diagnostic providing 2D tangential imaging of bremsstrahlung radiation from runaway electrons (RE) in the DIII-D tokamak. GRI is a lead pin-hole camera utilizing a 2D array of Bismuth Germanate (BGO) detectors. It is located at the DIII-D midplane and possesses up to 123 tangential sight-lines spanning the entire plasma poloidal cross-section. BGO detectors are sensitive to gamma-rays with energies 1−30 MeV, have sensitivity of 14 mV/MeV, energy resolution of 10%, and are able to distinguish pulses for pulse height analysis with 100 μs time resolution. This allows investigation of RE spatial and energy distribution evolution, which is critical to evaluating the importance of various RE dissipation mechanisms.A recent upgrade saw the number of instrumented GRI channels doubled (56) to image the entire plasma region, and additional lead shielding installed to reduce the flux of uncollimated gammas. Other detectors (BGO crystal coupled with Multi-Pixel Photon Counter (MPPC) and LYSO coupled with MPPC) were also investigated to improve the time resolution to 5 μs and 50 ns respectively. Measurements of bremsstrahlung radiation and comparison to synthetic diagnostics will be discussed.This work was supported by the US DOE under DE-FC02-04ER54698

Speaker: A. Lvovskiy (Oak Ridge Associated Universities)
• 10:30
10.8 Two-pass upgrade to the Thomson Scattering diagnostic on the Prototype Material Plasma Exposure eXperiment (Proto-MPEX) 1h 30m

The Thomson scattering (TS) diagnostic on the Proto-MPEX at ORNL has been upgraded to simultaneously measure electron temperature (Te) and density (ne) at two axial locations. After the first pass through the vacuum vessel, the existing laser beamline is re-collimated in atmosphere and rerouted into the vacuum vessel for the second pass. The upgrade will help diagnose axial Te and ne gradients between the 'central chamber' and the target region, which are located 1m and 2.5m downstream from the helicon RF source. TS measurements have given Te≈4-15eV and ne≈1-4e19/m^3 at the central chamber, and Te≈1-2eV and ne≈1-3e19/m^3 at the target. The upgrade also increases the number of sampling points at the target from one fiber to 5 fibers, measuring 3cm radially across the plasma column, and 25 fibers in the central chamber radially spanning 8cm. The intensified CCD camera is double triggered for each laser pulse: 1) to measure the TS and laser stray light, and 2) to measure the plasma background light, which contains nuisance emission lines and bremsstrahlung. Subtracting the background light from the TS photons improves the temperature and density measurements. Details of the diagnostic setup, axial and radial measurements, and areas for further optimization will be discussed.

Speaker: Nischal Kafle (The University of Tennessee-Knoxville)
• 10:30
10.9 Conceptual Design of a Heavy Ion Beam Probe Diagnostic for W7-X 2h

A Heavy Ion Beam Probe (HIBP) diagnostic on the Wendelstein 7-X (W7 X) superconducting stellarator will provide a unique ability to advance understanding of neoclassical and turbulent particle and energy transport. We present results of beam simulations which show that measurement signal levels, calculated using neo-classical density and temperature profiles with central densities up to 1020 m-3, will enable study in the eight W7-X reference magnetic configurations of the equilibrium plasma potential and Er at all radii, and ion-scale fluctuations of ne and potential in the outer plasma region. Elements of the diagnostic design include (1) a beam of thallium or cesium ions having a maximum energy of 2 MeV; (2) injection and detection of the beam through previously allocated ports; (3) a toroidal magnetic field in the + direction of W7-X; and (4) location of all HIBP system components outside of the W7 X cryostat. These design parameters can be realized using the accelerator and energy analyzer of the TEXT-U 2 MeV HIBP (which is now in Greifswald), and beam steering systems having smaller electrodes and electric fields (but higher voltages) than those of the TEXT-U diagnostic. This work is supported by US DoE Award DE-SC0013918.

Speakers: Thomas Crowley (Xantho Technologies, LLC), T.P. Crowley (Xantho Technologies, LLC), D.R. Demers (Xantho Technologies, LLC), P.J. Fimognari (Xantho Technologies, LLC), O. Grulke (Max-Planck-Institute for Plasma Physics), R. Laube (Max-Planck-Institute for Plasma Physics)
• 10:31
10.10 Analysis of systematic trends in experimental observables for direct-drive cryogenic targets on OMEGA 2h

A technique for identifying trends in performance degradation for inertial confinement fusion implosion experiments will be discussed. It is based on reconstruction of the implosion core with a combination of low- and mid-mode asymmetries. This technique was applied to the ensemble of hydro-equivalent deuterium--tritium implosions on OMEGA that achieved hot-spot pressures ≈56±7 Gbar.(1) The analysis suggests that in addition to low modes, that can cause a degradation of the stagnation pressure mid modes are present that reduce the size of the burn volume. The systematic analysis shows that asymmetries can cause an overestimation of the total areal density in these implosions. It is also found that an improvement in implosion symmetry resulting from correction of either the systematic mid or low modes would result in an increase of the hot-spot pressure from 56 Gbar to ≈80 Gbar. This material is based upon work supported by the Lawrence Livermore National Laboratory under subcontract B614207 and by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0001944. (1)S. Regan et al., Phys. Rev. Lett. 117, 025001 (2016)

Speaker: Arijit Bose (University of Michigan)
• 10:31
10.11 Prototyping and testing of the ITER plasma position reflectometry high-field side in-vessel antenna assembly 2h

The ITER Plasma Position Reflectometry diagnostic aims to provide measurements of the edge plasma to correct or supplement the magnetics for plasma position control. It consists of five systems, two of which are installed inside the vessel. One of these systems probes the plasma from the high-field side using small pyramidal horns located in the gap between two blankets. Electromagnetic simulations have shown that the blankets shape the radiation pattern and need to be considered as part of the antenna. Full-wave plasma simulations have shown that the first-wall geometry might induce measurement errors above the required ±1 cm. To further address these issues, we manufactured an antenna prototype that includes a mock-up of the blankets. Here, we present the results of the prototype tests in an anechoic chamber and using a target metallic mirror, with and without the blankets. The signals from varying target distances are used to assess the precision/accuracy of the system with time-frequency data analysis techniques employed to obtain automatic routine density profiles in current devices. The sensitivity to tolerances in the blankets’ installation is assessed by changing the height of the blankets’ gap as well as the antenna’s position with respect to their surfaces.

Speakers: Paulo Varela (Instituto de Plasmas e Fusão Nuclear, Instituto Superior Técnico, Universidade de Lisboa), António Silva (Instituto de Plasmas e Fusão Nuclear, Instituto Superior Técnico, Universidade de Lisboa), Jorge Belo (Instituto de Plasmas e Fusão Nuclear, Instituto Superior Técnico, Universidade de Lisboa)
• 10:31
10.12 First step towards a synthetic diagnostic for magnetic fluctuation measurements using cross-polarization scattering on DIII-D 2h

Cross-polarization scattering (CPS) provides localized magnetic fluctuation measurements in fusion plasmas based upon the process where magnetic fluctuations scatter electromagnetic radiation into the perpendicular polarization. The CPS system on DIII-D utilizes the probe beam of the Doppler backscattering (DBS) diagnostic and a crossing CPS receive beam, which allows simultaneous density and magnetic fluctuation measurements with good spatial resolution and wavenumber coverage. The interpretation of the signals is challenging due to the complex propagation of the DBS probing beam and CPS receive beam in plasmas. A synthetic diagnostic for CPS is therefore essential to interpreting data and detailed validation tests of non-linear turbulence simulations. This work reports a first step towards a synthetic diagnostic for CPS, utilizing GENRAY, a 3-D ray tracing code, to simulate the propagation of the DBS probing and CPS receive beam centers within the plasma. Results of probed wavenumbers in the current CPS system on DIII-D, and optimization of antenna locations and orientations for future system upgrades are presented. Work supported by USDOE Grants DE-FG02-08ER54984 and DE-FC02-04ER54698.

Speakers: Guiding Wang (University of California Los Angeles), T.L. Rhodes (University of California Los Angeles), N.A. Crocker (University of California Los Angeles), W.A. Peebles (University of California Los Angeles), K. Barada (University of California Los Angeles)
• 10:31
10.13 Laser-induced fluorescence diagnostic of Ion Temperature and Density profile imaging via Pulse lasers in an oxide coated cathode argon plasma 2h

An oxide coated cathode discharge has been characterized using laser-induced fluorescence (LIF) and Planar LIF. The ion temperature was measured in the center of an argon discharge by LIF diagnosis, and the ion density profiles was measured by PLIF diagnosis. Same Laser system consisting of a pumping pulse laser and a tunable dye laser was used in these two measurements. The absorption spectra measurements of a heated iodine cell are used to monitor the relative wavelength of the laser during the LIF measurement. The ion temperature was found to be about 0.5eV, which was close to the result of gridded electrostatic energy analyzers. The ion density profiles measured by PLIF and the electron density profiles measured by probes have similar structures, and PLIF offers higher spatial and temporal resolutions.

Speakers: qiaofeng zhang, jinlin xie (University of Science and Technology of China), ming luo (University of Science and Technology of China), feibin fan (University of Science and Technology of China), quanming lu (University of Science and Technology of China), Dongqi Han (Dept. of Modern Physics, university of science and technology of china)
• 10:31
10.14 Development of tracer contained compact toroid injection system 2h

In the development of magnetic confined fusion reactors, the accumulation of impurities is one of the most important subjects for concern because it potentially causes cooling down of the hot plasma. On the other hand, appropriate radiation from localized impurity might mitigate the heat load onto the divertor plate. The tracer-encapsulated solid pellet (TESPEL) has generated certain results in these studies. However, the TESPEL technique has several points to be improved, e.g. a penetration depth, increase in amount of the tracer impurity, and so on. In this study, tracer contained compact toroid (TCCT) injection system utilizing a magnetized coaxial plasma gun (MCPG) has been developed. Discharge current on the MCPG sputters and ionizes the electrode material such as tungsten and accelerate it by the Lorenz-self force. The MCPG easily accelerate the plasmoid higher than the ion thermal velocity of several tens km/s. The accelerated and ejected plasmoid containing tracer ions is warm ionized plasma itself. Therefore, the TCCT is potentially injected the core region of target plasma. Behavior of tracer ions in the compact toroid injected into the transverse magnetic field has been experimentally investigated.

Speakers: Daichi Kobayashi (Nihon University), Tomohiko Asai (Nihon University), Shodai Yamada (Nihon University), Yusai Ishikawa (Nihon University), Naoki Tamura (National Institute for Fusion Science), Yoshiro Narushima (National Institute for Fusion Science)
• 10:31
10.15 Improved Design of Local Oscillator Optics System For Electron Cyclotron Emission Imaging On J-TEXT 2h

A new electron cyclotron emission imaging (ECEI) which contains two 16-antenna arrays is being developed on J-TEXT. The mixers in the same antenna array will be driven by the same microwave source. So an optics system is needed to expand the point source to an elongated line source. A traditional spherical local oscillator (LO) optics used to be designed to couple the LO signals and RF power into 16 vertical antennas. There are many limitations which include but not limit to: the driving power to the mixers of the edge channels, the collimation of the LO signal, the restricted optical path length, and so on. Therefore the traditional spherical LO optics on J-TEXT has some modification based on these questions. In addition, an advanced aspheric lens called Powell lens is employed to supersede the traditional one. Powell lens optics not only has the same advantages of traditional spherical LO optics, but also realizes the uniform distribution of LO power on the antennas. The length from LO source to antenna arrays is about 1.1m. And a new 3-pieces Powell LO optics which improves the robustness of 2-pieces Powell LO optics will be introduced. Furthermore, a presentation for simulation results and comparison of these LO optics will be given in this paper.

Speakers: Xianli Xie (Huazhong University of Science and Technology ), Zhoujun Yang (Huazhong University of Science and Technology ), Xiaoming Pan (Huazhong University of Science and Technology ), Jing Zhou (Huazhong University of Science and Technology ), Hao Zhou (Huazhong University of Science and Technology ), Ge Zhuang (University of Science and Technology of China)
• 10:31
10.16 Further Studies of the Analogue Saturation Limit of MCP-PMTS 2h

Photek are a well-established supplier of microchannel plate (MCP) photomultiplier tubes (PMT) to the inertial confinement fusion community, and have several detectors installed at NIF, Omega (LLE Rochester) and Orion (AWE). The MCP-PMTs produced by Photek have the shortest response time recorded by devices of this type with a small area single MCP PMT having a FWHM of < 100 ps, and in recent years we have also made significant improvements to their gating ability. The analogue signals produced at the major ICF facilities cover many orders of magnitude and often need multiple detectors operating at different levels of electron gain. As such, understanding the upper saturation limit of MCP-PMTs to large, low rate signals takes on a high importance. A previous study looked at the saturation limit of double and single MCP-PMTs over their full working area with pulse widths between 4 ns and 100 ns. This follow-on analysis will look at the effect of how the illuminated area affects the saturation limit, and how the saturation behaves from pulse widths from 4 ns down to the PMT limit of ~ 100 ps.

Speakers: James Milnes (Photek Ltd), Tom Conneely (Photek Ltd), Colin Horsfield (Atomic Weapons Establishment), Jon Lapington (University of Leicester)
• 10:31
10.17 The lithium beam as a diagnostic tool for measurement of current density, electron and impurity density, and main ion temperatures in an H-mode pedestal 2h

The lithium beam is an effective diagnostic tool for investigation of stability and particle transport in the pedestal. It was used successfully to measure edge current density12 on DIII-D, achieving qualitative agreement with neoclassical models. Electron density profiles were also measured3. Proposed upgrades will continue these measurements with higher reliability as well as explore new applications such as measurement of impurity and main ion density and temperature using charge exchange emission, and edge current measurements using high resolution spectroscopy. Beam performance will be optimized using new lithium sources, beam tuning, and monitoring. The optics will be redesigned to optimize throughput and aperture broadening, and to replace the PMTs with APDs. New techniques will be developed for background subtraction, using beam modulation and background monitoring. The new system will yield detailed measurements of the pedestal, complementing existing diagnostics for investigating pedestal stability, ELM cycle, and particle transport through the pedestal. *Supported by US DOE DE-FG03-96ER54373 and DE-FG02-97ER54415 1D.M. Thomas. AIP Conf. Proc. 926, 56 (2007) 2D.M. Thomas, et al, Phys. Plasmas 12, 056123 (2005) 3H. Stoschus, et. al. Rev. Sci. Instrum. 83, 10D508 (2012)

Speakers: Ken Liao (University of Texas at Austin), Max Austin (University of Texas at Austin), William Rowan (University of Texas at Austin), Dan Thomas (General Atomics), Bingzhe Zhao (University of Texas at Austin)
• 10:31
10.18 Laser Calibration of the DIII-D Coherence Imaging System 2h

In this paper we describe an in-situ calibration technique for the Coherence Imaging Systems (CIS) that measure 2-D images[1] of plasma ion flows[2] on DIII-D. A low power CW diode laser that is tuneable in the range 464-467 nm along with a precision wavemeter (0.01 pm resolution) is used to characterize the interferometer phase as a function of wavelength in the region of CIII (465 nm) and He II (468 nm). The interferometer is stabilized both mechanically and thermally to minimize drift during the calibration. Optical stirring and a labsphere are used to obtain spatially uniform calibration images. The quality of the calibration data enables a measurement of both linear and quadratic terms over approximately 10 fringes of the interferometer. These coefficients can also be related to the geometry of the optics and the birefringent crystal of the interferometer. On DIII-D, the labsphere is inserted into the CIS optical system between shots and the calibration data is automatically recorded. Work supported by the US DOE under DE-FC02-04ER54698 and DE-AC52-07NA27344. [1] W.H. Meyer, et al., these proceedings (invited). [2] C.M. Samuell, et al., these proceedings (invited).

Speakers: Allen Steven (LLNL), Cameron Samuell (LLNL@GA), William Meyer (LLNL), John Howard (ANU)
• 10:31
10.19 Multi-frame radiography using the Crystal Backlighter Imager coupled to a new Single Line of Sight camera on the National Ignition Facility 2h

The Crystal Backlighter Imager (CBI) is a monochromatic x-ray radiography diagnostic developed with the goal of imaging the late stages of inertial confinement fusion implosions on the NIF. Initially, CBI could only provide a single radiograph per crystal x-ray optic per experiment given the use of a microchannel plate camera as the detector. The Single-Line-of-Sight (SLOS) framing camera is a transformative diagnostic that records a sequence (2-4) of fast-gated (100-35ps) x-ray images along the same line of sight. CBI has recently been coupled to SLOS, which increased the data output to multiple radiographs from a single crystal x-ray optic per NIF shot. Results will be presented from several experiments used to commission the coupling of CBI to SLOS. Spatial resolution as a function of backlighter standoff was measured by radiographing test objects. Timing calibration was achieved by comparing SLOS radiographs to one from the microchannel plate camera, whose timing was known to high accuracy, on two nominally-identical capsule implosions shots. Lawrence Livermore National Laboratory is operated by Lawrence Livermore National Security, LLC, for the U.S. Department of Energy, National Nuclear Security Administration under Contract DE-AC52-07NA27344. Release # LLNL-ABS-744383.

Speakers: Gareth Hall (Lawrence Livermore National Laboratory), Christine Krauland (General Atomics), Sabrina Nagel (Lawrence Livermore National Laboratory), Justin Buscho (Lawrence Livermore National Laboratory), Nathaniel Thompson (Lawrence Livermore National Laboratory), Arthur Carpenter (Lawrence Livermore National Laboratory), Matthew Dayton (Lawrence Livermore National Laboratory), Robin Hibbard (Lawrence Livermore National Laboratory), Perry Bell (Lawrence Livermore National Laboratory), David Bradley (Lawrence Livermore National Laboratory), Otto Landen (Lawrence Livermore National Laboratory), Shannon Ayers (Lawrence Livermore National Laboratory), Thomas McCarville (Lawrence Livermore National Laboratory), Benjamin Hatch (Lawrence Livermore National Laboratory), Joe Holder (Lawrence Livermore National Laboratory), Emily Hurd (Lawrence Livermore National Laboratory), Daniel Kalantar (Lawrence Livermore National Laboratory), Thomas Kohut (Lawrence Livermore National Laboratory), Roger Lowe-Webb (Lawrence Livermore National Laboratory), Robert Petre (Lawrence Livermore National Laboratory), Kenneth Piston (Lawrence Livermore National Laboratory), Kyle Engelhorn (General Atomics), Terance Hilsabeck (General Atomics)
• 10:31
10.20 Development of a multi-pinhole point-backlit-radiography source 2h

Laser-irradiating a foil to create a radiation source is a common procedure in high-energy-density experiments. Foil radiation sources are used to drive physical phenomena or diagnostics - such as radiography. Radiography images measure the reduction in intensity of a radiation source through an object, which implies a line-integrated density. Point backlit radiography requires that a pinhole is placed between the laser-irradiated foil and the object to image. The pinhole size and placement controls radiation uniformity, image magnification and resolution. However, point backlit radiography is limited by the amount of data it can collect, typically one image per axis.We present our first design and results from a multi-pinhole backlit radiography source. The pinholes coexist on the same substrate and are independently triggered 2 ns apart. A 100 micron titanium wall separates the pinholes on the laser irradiated substrate.This work is funded by the U.S. DOE, through the NNSA-DS and SC-OFES Joint Program in HEDPLP, grant No. DE-NA0002956, and the NLUF Program, grant No. DE-NA0002719, and through LLE, University of Rochester by the NNSA/OICF under Cooperative Agreement No. DE-NA0001944. This work is funded by the Lawrence Livermore National Laboratory under subcontract B614207.

Speakers: Robert VanDervort (University of Michigan), Matthew Trantham (University of Michigan), Sallee Klein (University of Michigan), Chuck Sorce (Laboratory for Laser Energetics), Paul A. Keiter (University of Michigan), R. Paul Drake (University of Michigan)
• 10:31
10.21 Surface eroding thermocouples for fast heat flux measurement in DIII-D 2h