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...
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...
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 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...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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....
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...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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....
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...
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...
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...
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...
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...
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...
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...
