The measurement of supper thermal electron population is an important issue for the study of runaway electrons in the low density discharges or during the disruptions in tokamak plasmas. The fast electron bremsstrahlung (FEB) emissions resulted from the interaction between the low energy runaway electrons and the bulk plasma can provide significant information on the runaway generation...
In our previous works, the multichannel three-wave polarimeter-interferometer system (POLARIS) on J-TEXT tokamak has been exploited to measure far-forward collective scattering (FCS) from electron density fluctuations [1]. Most recently, some substantial improvements have been completed. Firstly, the data processing is optimized, so that the low-frequency density fluctuations (<20kHz) could be...
In order to optimize the scientific exploitation of JET during the upcoming deuterium-tritium experiments, a set of diagnostic systems is being enhanced. These upgrades focus mainly on the experimental and operational conditions expected during tritium campaigns. It should be stressed that measurements relevant for burning plasmas are specifically targeted. Previously non-existing...
Relative intensity calibration for the KSTAR beam emission spectroscopy (BES) system is successfully achieved with a fast visible CMOS camera. The KSTAR BES system with 2D array (4×16) avalanche photodiode (APD) detectors is allowed to move its spatial position of measurements and rotate its orientation to study plasma turbulence at various spatial positions. A proper relative intensity...
Ion cyclotron emission (ICE) is a commonly observed feature of magnetized toroidal plasmas in the presence of fast ions. It is generally agreed that this emission is caused by an inverted velocity distribution of confined fast ions originating from either neutral beam injection (NBI), fusion reactions, or acceleration by waves in the ion cyclotron range of frequencies (ICRF). As a result, ICE...
A high speed solid-state framing camera has been developed which can operate over a wide range of photon energies. This camera measures the change in the index of refraction of a semiconductor when photons with energies higher than the bandgap are incident upon it. This instrument uses an binary grating in front of the semiconductor to impose a corresponding grating in the semiconductor when...
Synthetic diagnostics are aimed at simulating the responses of diagnostic systems under real experimental scenarios and are the key to drawing quantitative inferences from experimental data. The synthetic ECEI diagnostic is suitable to evaluate the improvement arising from the application of Field Curvature Adjustment (FCA) lenses in the design of the upgraded EAST ECEI system. Previously, a...
Single-shot, x-ray diffraction measurements to characterize phase transitions of dynamically compressed, high-Z materials at Mbar pressures require both sufficient photon energy and flux to record data with high fidelity. Besides x-ray lasers and synchrotrons, large-scale laser systems are used to generate brilliant x-ray sources above 10 keV by utilizing line radiation of mid-Z elements....
Measurements were performed on bending magnet beam line 9.3.1 at the Advanced Light Source (Lawrence Berkeley National Laboratory, Berkeley, CA, USA) over the energy range of approximately 2.5 to 8 keV. A dual goniometer endstation was used to measure crystal diffraction properties for the potassium acid phthalate (KAP). The measurement results are subsequently compared to a crystal...
High current modulations are widely required in tokamaks to generate specific magnetic field for plasma confinement, which are challenges for power electronics. For high current modulation, the stray inductance will cause high noise and surge voltage that may damage the power electronics. In addition, it is difficult to ensure both a fast response and a steady evolution. In this paper, a power...
A new tool has been developed to calculate the spectral, spatial and temporal response of multi-energy soft x-ray (ME-SXR) pinhole cameras for arbitrary plasma densities (ne,D), temperature (Te) and impurity densities (nZ). ME-SXR imaging provides a unique opportunity for obtaining important plasma properties (e.g. Te, nZ and Zeff) by measuring both continuum- and line emission in multiple...
Important plasma-surface processes in burning plasmas include erosion due to physical and chemical sputtering, material redeposition and transport, mechanical failure, and other unique topics such as fuel recycling, tungsten fuzz formation, tritium retention, all of which are wall-material dependent and highly dynamic. It is also anticipated that better understanding through in-situ...
Plasma radiation is a crucial parameter for particle and energy transport study in fusion plasmas. Infrared imaging video bolometers (IRVB) can provide radiation profiles of fusion plasmas with noise stability, flat sensitivity and wide viewing range. Since the raw data of IRVB is the sum of local emissivity along the line of sight, tomographic reconstruction for removing line-integration...
IShTAR is a linear device dedicated to the investigation of the edge plasma - ICRF antenna interactions in tokamak edge-like conditions and serves as a platform for a diagnostic development for measuring the electric fields in the vicinity of ICRF antennas. We present here our progress in the development of an optical emission spectroscopy method for measuring the electric fields which...
The Divertor Langmuir Probes (DLP) on ITER will be used for machine control - helping to ascertain attached/detached plasma conditions – as well as for physics studies of the divertor plasma parameters. The severe environment of the divertor region, in particular the high photon radiation loads, presents a particular challenge to the probe design. The photon load averages several W/mm^2 on the...
The infrared imaging video bolometer (IRVB) as a foil bolometry technique can be an alternative solution to the conventional resistive bolometer since it has a great advantage in its stability against electromagnetic noise compared with resistive bolometers using a Wheatstone Bridge. As for the data analysis of the IRVB, the plasma 2D radiation profile is not directly converted from the foil...
Xiaoyi Yang, Tianchao Xu, Yihang Chen, Tianbo Wang, Chijie Xiao, Min Xu, Yi Yu, Xiaogang Wang
The Laser-driven Ion-beam Trace Probe (LITP) is a new Bp diagnostic method, firstly proposed in 2014. The basic principle of the LITP method is as follow. Ions generated by laser-driven accelerator are injected into the tokamak, passing through the plasma and finally reached the detector on the vacuum...
A series of experiments carried out with Ne seeding on JET with the ITER-like-Wall (ILW) suggests increased tungsten release and impurity accumulation as consequences of Ne seeding. For this reason, a detailed study of impurity behaviour together with its control during light gas injection is required. This paper reports on impurity behaviour in a set of hybrid discharges with Ne using the...
Determining fuel areal-density asymmetries is vital to assessing the performance for inertial confinement fusion implosions. The Charged Particle Spectrometry Suite (CPS’s) at the OMEGA facility has been used to infer the fuel areal-density asymmetries in cryogenic deuterium-tritium implosions by measuring the spectrum of knock-on deuterons in different directions. These knock-on deuterons ...
The shape and position of Tokamak plasma play a crucial role in controlling the steady-state operation. Due to the high speed and good visual effect, a high-speed CCD is used for observing the configuration of plasma on Experimental Advanced Superconducting Tokamak (EAST). According to the layout of EAST diagnostics window, the large field of view visible and infrared integrated endoscopy...
We present multi-dimensional reconstruction of spatial profiles of plasma conditions by analyzing spectrally resolved x-ray image data obtained from OMEGA direct-drive ICF implosions. The targets were spherical plastic shells filled with varying D2-Ar relative and total gas pressures, similar to previous recent experiments [1]. Argon K-shell spectral features were observed primarily between...
A supersonic gas-jet target platform has been activated on the OMEGA laser. The plasma formed using a gas-jet target and ~3 kJ of UV energy from the OMEGA Laser System was characterized using 2ω Thomson scattering. Thomson scattering provided accurate time-resolved measurements of plasma conditions including electron density, plasma temperature, and ionization state. Plasma conditions include...
Characterization of plasma structure and density is critical for diagnosis and control of C-2W plasma equilibria. To this end, two compact, highly portable, turnkey second harmonic interferometers[1] are used to make measurements with greater flexibility than available from other diagnostics, providing important information sooner than what would be possible from more complicated systems and...
A graphite element, called a scraper [1], will be installed in 2018 on the Wendelstein 7-X stellarator in the throat of the divertor (at two out of ten potential toroidal locations). We have designed, built, and calibrated a new infrared/visible imaging endoscope system to enable detailed observations of the plasma interactions and heat loads at one of the scrapers, and the neighboring...
Two filtered fast-imaging instruments, with radial and axial views, respectively, were used on the C-2U device to visualize line emission from impurities and hydrogenic neutrals. Due to the accelerated pace of C-2U operations, in-vessel access was not available; as a result, novel calibration techniques needed to be developed. Spatial calibration involved optimizing parameters in a generic...
The Thin foil Proton Recoil spectrometer (TPR) concept has previously been used at JET as a DT fusion neutron diagnostic. It is also one of the techniques suggested for use at ITER as part of the high resolution neutron spectrometer system. The main purpose of the neutron spectrometers at ITER is to determine the fuel ion density ratio in DT plasmas. The TPR principle is based on the...
Lasers incident on solid targets produce B-fields around the laser spot due to orthogonal ne and Te gradients that develop near the target surface[1]. Simulations show that these fields are produced in hohlraum experiments at the NIF[2], and that the presence of B-fields can affect particle and energy transport. Little work exists comparing simulated fields predicted by MHD models to data at...
Local measurements of electrostatic and magnetic turbulence (~E and ~B) in fusion grade plasmas are a critical missing component in advancing our understanding of turbulent transport. A novel diagnostic for measuring these fluctuations is being developed. It employs high-speed measurements of the spectral linewidth of the Motional Stark Effect split neutral beam emission, where the amount of...
A fundamental component of any magnetically confined fusion experiment is a firm understanding of the magnetic field. The increased complexity of the C-2W machine warrants an equally enhanced diagnostic capability. C-2W is outfitted with over 700 magnetic field probes of various types. They are both internal and external to the vacuum vessel. Inside, a linear array of innovative in-vacuum...
The magnetic field on a closed surface can be uniquely decomposed into contributions from currents internal and external to the surface [A.H. Boozer, Nucl. Fusion 55, 025001 (2015)]. In the context of a magnetic fusion device, this general principle implies that given a sufficient set of magnetic diagnostics just outside the plasma surface, the plasma’s contribution to the magnetic field can...
"TAE’s advanced, beam-driven field-reversed configuration device has a large fast-ion population, allowing for fast-ion D-alpha (FIDA) studies. Development of a FIDA spectrometer for the new C-2W device is underway. Previous measurements [1] were combined with C-2W geometry to inform the design. Measured signal levels led to the purchase of a Phantom Miro 110 high-speed camera that will be...
X-ray radiography is a powerful tool for diagnosing high energy density states. In particular, face-on X-ray radiography is used in material strength experiments on the NIF. In these experiments, Rayleigh-Taylor (RT) growth is monitored in samples with pre-formed ripples driven to high pressure with the departure from classical RT growth attributed to material strength. In this experiment, the...
Measurements of fusion neutron spectrometry is a useful diagnostic for DD neutron yield from 109 to 1015 n/s for EAST deuterium plasma discharges with NBI, LHWl, ICRF heating and their combination. A suite of compact neutron spectrometers, based on liquid scintillators and a stilbene crystal detector has been implemented on EAST for lower yield neutron measurements, and the ion temperature...
A prototype of an infrared imaging bolometer (IRVB) was successfully deployed and tested on the Alcator C-Mod tokamk during the end of the FY16 campaign. The IRVB method interprets the power radiated from the plasma by measuring the temperature rise of a thin, 2.5 micron Pt absorber that is exposed, through a pinhole aperture, to the full-spectrum of plasma photon emission. The IRVB was...
Fielding the 3rd Generation Gas Cherenkov Detector (GCD3) onto the National Ignition Facility (NIF) encompassed commissioning of the WellDIM3.9m Insertion Manipulator at Port 64-275 of the NIF Target Chamber. Phase II enhancements include the integration of the Sydor/Kentech/Photek Pulse-Dilation Photomultiplier Tube (PD-PMT) onto the existing detector. Given the 10x measurement bandwidth...
The C-2W experiment at TAE Technologies aims at sustaining an advanced beam-driven field reversed configuration (FRC) plasma. However, FRC lifetime is limited by particle confinement, among other factors. Injecting a supersonic compact toroid (CT) through the separatrix radius (Rs) is a means of refueling the FRC’s core with deuterium. For long-lived plasmas there is a need for multiple,...
Interferometry as one of the most common core fusion diagnostics has traditionally suffered from incomplete vibration compensation. Dispersion interferometry promises a more complete compensation of vibrations. For this reason it is being employed in an increasing number of experiments. However, thus far none of them have shown reliable real-time low-latency processing of dispersion...
As magnetically confined plasmas progress towards ignition and very long pulse experiments, the physics of the pedestal and diverter regions has become increasingly important. In particular, measurements of the ions in the scrape-off layer are needed. The energy spectra of the ions determines the rates of sputtering and erosion of the plasma facing surfaces. The ion spectra in the edge are not...
A motional Stark effect (MSE) imaging diagnostic was benchmarked against existing conventional MSE polarimeters on DIII-D and delivered new capabilities for measuring the magnetic pitch angle from 2 neutral beams and on the low field side of DIII-D. For 30 years conventional photoelastic modulator polarimeters have been used for constraining the toroidal current profile in fusion devices,...
Streak Cameras are an essential diagnostic tool used in shock physics and high energy density physics experiments. Such experiments require well calibrated temporally resolving diagnostics for studying events that occur on the nanosecond to microsecond time scales. The Nevada National Security Site (NNSS) and Sandia National Laboratories (SNL) have built a 42-channel solid state streak...
General Fusion is assembling an upgraded Thomson scattering system in preparation for measurements on the new PI3 plasma injector. Major changes include a shift of laser wavelength from 532 nm to 1064 nm and switching from a spectrometer and photomultiplier detector setup to polychromator and avalanche photodiode (APD) detector setup. A novel, inexpensive, tunable polychromator design will be...
A compact neutron spectrometer, based on a CH foil for production of recoil protons and CR-39 detection, is being developed for measurements of DD-neutron spectra at Z. To accurately measure the DD ion temperature (Tion) of ~2 keV, the spectrometer must have an energy resolution (FWHM) of ~120 keV. Spectral broadening is primarily dominated by the finite thickness of the converter foil and...
Passive spectroscopic measurements of Zeeman splitting has been reliably used to measure magnetic fields in plasmas for decades. However, a requirement is that the field must be high enough to be resolved over Doppler and instrument broadening (typically >1 T). A synthetic diagnostic capable of measuring low magnetic fields (<5 mT) with high sensitivity (+/- 0.5 mT) is currently under...
In fusion devices, subtle changes at the plasma edge (pedestal and scrape-off layer) can have a dramatic influence on confinement performance and anomalous transport properties of the plasma. In order to better understand physical processes happening in this region, we describe a detailed analysis of a novel diagnostic allowing the direct measurement of the local radial electric fields in the...
The detection of x-rays in the 100s of keV to MeV range for picosecond laser-matter interactions provides understanding of the laser to relativistic electron coupling, which is critical for applications such as Compton radiography, positron-electron pair production, and TNSA proton generation. Spectroscopy in the range of 0.1-2 MeV is difficult due to the high photon flux for single counting...
The instrument response function of neutron time-of-flight (nToF) systems is a major contributor to both systematic and statistical uncertainties of derived quantities of interest. In particular, the first and second moments of these distributions are associated with arrival time, t0, and ion temperature Tion. Response times of Cerenkov radiators recently deployed at NIF are set by neutron...
Electron-lattice coupling strength governs the energy transfer between electrons and lattices and is important for understanding the material behavior under thermal non-equilibrium conditions. Here we employed time-resolved electron diffraction at MeV energies to directly study the electron-lattice relaxation in 40-nm-thick polycrystalline copper excited by femtosecond optical lasers. The...
In order to effectively carry out the research of Plasma turbulence，a multichannel correlation reflectometry has been developed on EAST tokamak , which working in the frequency range of (20GHz-60GHz) and with the polarization of ordinary mode. The system can probe eight different radial locations simultaneously by launching eight fixed frequencies (20.4GHz,24.8GHz,33GHz,40GHz...
Reliable electric field measurements in a plasma are challenging, especially when fine resolution of spatial structure is critical. A capacitive probe [Mingsheng, Tan, et al. Rev. Sci. Instrum 88, 023502 (2017)] is one of a few diagnostics that are directly sensitive to the plasma potential. In such a probe, a boron nitride ceramic (BN) covers an electrode and a capacitor is formed between the...
The Orion high-resolution X-ray (OHREX) focusing, imaging spherically bent crystal spectrometer, operated with both image plates and CCD cameras, has been providing time-averaged plasma diagnostics through high-resolution spectroscopy with good signal-to-noise at the Orion Laser facility. For the next step towards time-resolved plasma diagnostics to be achieved by using the OHREX in...
As for studying the behavior of the turbulence affecting transport, the multi-scale turbulence interaction is receiving much attention at present. For this aim, higher spatial and temporal resolution diagnostics have been developed and applied in several devices [1]. In LHD, such the precise spatio-temporal behavior of turbulence flow velocity and intensity has been measured by the...
Currently Chinese Fusion Engineering Test Reactor (CFETR) has completed its physical design and started the phase of engineering design. To make transfer easier from Phase I to Phase II with the same machine, a larger size with R = 6.6 m/a = 1.8 m, BT = 6–7 T has been chosen. Diagnostic port plug, as one important part for reactor, will provide a common platform to support or contain variety...
The conditions and dynamics of neon gas puff z-pinch plasmas at pinch time are studied on COBRA, Cornell’s pulsed power generator (current rise time of ~240 ns and ~0.9 MA peak current). A 526.5 nm, 10 J Thomson scattering diagnostic laser enables probing of the plasma conditions of these implosions with both spatial and temporal resolution. The use of two laser pulses--both 3 ns in...
Proto-MPEX is a prototype design for the Material Plasma Exposure eXperiment (MPEX), a steady-state linear device being developed to study plasma material interactions (PMI). The primary purpose of Proto-MPEX is developing plasma heating source concepts for MPEX, which include a 13.56 MHz half-turn copper helicon antenna surrounding an aluminum nitride (AlN) window, whose strong...
We report temporally resolved, simultaneous measurements of the turbulent Reynolds Stresses in both the parallel and perpendicular directions and the corresponding particle fluxes in the fusion relevant cylindrical magnetized plasma device Controlled Shear Decorrelation eXperiment (CSDX). CSDX simulates the plasma conditions of and multiple plasma instabilities that can arise in the scrape off...
