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...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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,...
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...
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...
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...
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 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...
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...
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...
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....
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...
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...
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....
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,...
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...
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...
"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,...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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 =...
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...
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...
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...
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...
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....
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...
