HTPD 2018

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

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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)

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)

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.

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.

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

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.

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

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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)

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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

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

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.

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.

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.

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.

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.

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.

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

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.

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.

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.

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

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

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.

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.

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.

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

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)

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.

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.

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

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.

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.

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.

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.

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.

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.

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

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.

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.

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.

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.

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.

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.

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.

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.

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.

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).

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/

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.

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.

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.

"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)."

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

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

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.

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.

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

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.

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.

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.

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.

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.

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.

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.

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.

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

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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)

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.

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.

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.

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.

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.

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.

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)

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.

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.

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.

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.

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

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.

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.

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.

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.

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.

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.

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.

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.

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.

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).

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

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.

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.

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.

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.

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.

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.

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

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).

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.

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.

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.

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

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.

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.

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.

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.

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.