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Plasma light

S D Scott, R T Mumgaard
A tokamak-independent analysis suite has been developed to process data from Motional Stark Effect (mse) diagnostics. The software supports multi-spectral line-polarization mse diagnostics which simultaneously measure emission at the mse σ and π lines as well as at two "background" wavelengths that are displaced from the mse spectrum by a few nanometers. This analysis accurately estimates the amplitude of partially polarized background light at the σ and π wavelengths even in situations where the background light changes rapidly in time and space, a distinct improvement over traditional "time-interpolation" background estimation...
November 2016: Review of Scientific Instruments
T M Biewer, S Meitner, J Rapp, H Ray, G Shaw
A Thomson scattering (TS) diagnostic has been successfully implemented on the prototype Material Plasma Exposure eXperiment (Proto-MPEX) at Oak Ridge National Laboratory. The diagnostic collects the light scattered by plasma electrons and spectroscopically resolves the Doppler shift imparted to the light by the velocity of the electrons. The spread in velocities is proportional to the electron temperature, while the total number of photons is proportional to the electron density. TS is a technique used on many devices to measure the electron temperature (Te) and electron density (ne) of the plasma...
November 2016: Review of Scientific Instruments
J S Ross, P Datte, L Divol, J Galbraith, D H Froula, S H Glenzer, B Hatch, J Katz, J Kilkenny, O Landen, A M Manuel, W Molander, D S Montgomery, J D Moody, G Swadling, J Weaver
An optical Thomson scattering diagnostic has been designed for the National Ignition Facility to characterize under-dense plasmas. We report on the design of the system and the expected performance for different target configurations. The diagnostic is designed to spatially and temporally resolve the Thomson scattered light from laser driven targets. The diagnostic will collect scattered light from a 50 × 50 × 200 μm volume. The optical design allows operation with different probe laser wavelengths. A deep-UV probe beam (λ0 = 210 nm) will be used to Thomson scatter from electron plasma densities of ∼5 × 10(20) cm(-3) while a 3ω probe will be used for plasma densities of ∼1 × 10(19) cm(-3)...
November 2016: Review of Scientific Instruments
M L Reinke, M Han, G Liu, G G van Eden, R Evenblij, M Haverdings, B C Stratton
Measurements of radiated power in magnetically confined plasmas are important for exhaust studies in present experiments and expected to be a critical diagnostic for future fusion reactors. Resistive bolometer sensors have long been utilized in tokamaks and helical devices but suffer from electromagnetic interference (EMI). Results are shown from initial testing of a new bolometer concept based on fiber-optic temperature sensor technology. A small, 80 μm diameter, 200 μm long silicon pillar attached to the end of a single mode fiber-optic cable acts as a Fabry-Pérot cavity when broadband light, λo ∼ 1550 nm, is transmitted along the fiber...
November 2016: Review of Scientific Instruments
H B Ray, T M Biewer, D T Fehling, R C Isler, E A Unterberg
Fast visible cameras and a filterscope are used to examine the visible light emission from Oak Ridge National Laboratory's Proto-MPEX. The filterscope has been configured to perform helium line ratio measurements using emission lines at 667.9, 728.1, and 706.5 nm. The measured lines should be mathematically inverted and the ratios compared to a collisional radiative model (CRM) to determine Te and ne. Increasing the number of measurement chords through the plasma improves the inversion calculation and subsequent Te and ne localization...
November 2016: Review of Scientific Instruments
L B Fletcher, U Zastrau, E Galtier, E J Gamboa, S Goede, W Schumaker, A Ravasio, M Gauthier, M J MacDonald, Z Chen, E Granados, H J Lee, A Fry, J B Kim, C Roedel, R Mishra, A Pelka, D Kraus, B Barbrel, T Döppner, S H Glenzer
We present the first spectrally resolved measurements of x-rays scattered from cryogenic hydrogen jets in the single photon counting limit. The 120 Hz capabilities of the LCLS, together with a novel hydrogen jet design [J. B. Kim et al., Rev. Sci. Instrum. (these proceedings)], allow for the ability to record a near background free spectrum. Such high-dynamic-range x-ray scattering measurements enable a platform to study ultra-fast, laser-driven, heating dynamics of hydrogen plasmas. This measurement has been achieved using two highly annealed pyrolytic graphite crystal spectrometers to spectrally resolve 5...
November 2016: Review of Scientific Instruments
T Bando, S Ohdachi, Y Suzuki
Multi-channel soft x-ray (SX) diagnostic has been used in the large helical device (LHD) to research magnetohydrodynamic equilibria and activities. However, in the coming deuterium plasma experiments of LHD, it will be difficult to use semiconductor systems near LHD. Therefore, a new type of SX diagnostic, a scintillator-based type diagnostic, has been investigated in order to avoid damage from the radiation. A fiber optic plate coated by P47 scintillator will be used to detect SX emission. Scintillation light will be transferred by pure silica core optical fibers and detected by photomultiplier tubes...
November 2016: Review of Scientific Instruments
D B Schaeffer, C G Constantin, A S Bondarenko, E T Everson, C Niemann
We present optical Thomson scattering results that image for the first time in a single measurement the spatial transition from collective to non-collective scattering. Data were taken in the Phoenix laser laboratory at the University of California, Los Angeles. The Raptor laser was used to ablate a carbon plasma, which was diagnosed with the frequency-doubled Phoenix laser serving as a Thomson scattering probe. Scattered light was collected from the laser plasma up to 10 cm from the target surface and up to 10 us after ablation, and imaged with high spatial and spectral resolutions...
November 2016: Review of Scientific Instruments
Yinan Zhou, Li Gao, Jiefeng Huang, Qingshuang Qiu, Ge Zhuang
An infrared multi-channel Thomson scattering diagnostic system is designed from the viewpoint of development of the proposed system on the Joint Texas Experimental Tokamak (J-TEXT). A 3 J/50 Hz Nd:YAG laser, which is injected vertically into plasma in the direction from top to bottom, serves as the power source of the system. The scattering light is then collected horizontally and is transmitted to an interference-filter avalanche photodiode based polychromater for spectrum analysis. The system covers the half plasma cross section, providing 14 spatial points with 2 cm resolution...
November 2016: Review of Scientific Instruments
C H Liu, Y Huang, Y Q Wang, Z Feng, Z P Hou, B Z Fu
The edge tangential Thomson scattering system (ETTSS) was developed for the first time on a HL-2A tokamak. A Nd:YAG laser with a 1064 nm wavelength, 4 J energy, and 30 Hz repetition rate is employed on the ETTSS. The laser beam injects the plasma in the tangential direction on the mid-plane of the machine, and the angles between the laser injection direction and the scattered light collection direction are in the range from 157.5° to 162.8°. The scattered light collection optics with 0.21-0.47 magnification is utilized to collect the scattered light of measurement range from R = 1900 mm to 2100 mm (the normalized radius is from r/a = 0...
November 2016: Review of Scientific Instruments
E R Scott, R Barchfeld, P Riemenschneider, C W Domier, C M Muscatello, M Sohrabi, R Kaita, Y Ren, N C Luhmann
The Far-infrared Tangential Interferometer/Polarimeter (FIReTIP) system has been refurbished and is being reinstalled on the National Spherical Torus Experiment-Upgrade (NSTX-U) to supply real-time line-integrated core electron density measurements for use in the NSTX-U plasma control system (PCS) to facilitate real-time density feedback control of the NSTX-U plasma. Inclusion of a visible light heterodyne interferometer in the FIReTIP system allows for real-time vibration compensation due to movement of an internally mounted retroreflector and the FIReTIP front-end optics...
November 2016: Review of Scientific Instruments
R K Follett, J A Delettrez, D H Edgell, R J Henchen, J Katz, J F Myatt, D H Froula
Collective Thomson scattering is a technique for measuring the plasma conditions in laser-plasma experiments. Simultaneous measurements of ion-acoustic and electron plasma-wave spectra were obtained using a 263.25-nm Thomson-scattering probe beam. A fully reflective collection system was used to record light scattered from electron plasma waves at electron densities greater than 10(21) cm(-3), which produced scattering peaks near 200 nm. An accurate analysis of the experimental Thomson-scattering spectra required accounting for plasma gradients, instrument sensitivity, optical effects, and background radiation...
November 2016: Review of Scientific Instruments
F Glass, T N Carlstrom, D Du, A G McLean, D A Taussig, R L Boivin
A design to extend the unique divertor Thomson scattering system on DIII-D to allow measurements of electron temperature and density in high triangularity plasmas is presented. Access to this region is selectable on a shot-by-shot basis by redirecting the laser beam of the existing divertor Thomson system inboard - beneath the lower floor using a moveable, high-damage threshold, in-vacuum mirror - and then redirecting again vertically. The currently measured divertor region remains available with this mirror retracted...
November 2016: Review of Scientific Instruments
R F Kelly, K D Meaney, M Gilmore, T R Desjardins, Y Zhang
In order to investigate the role of both neutral and ion dynamics in large-scale helicon discharges, a laser induced fluorescence (LIF) system capable of measuring both ArI and ArII fluorescence using a single tunable laser is being developed. The system is based on a >250 mW solid state laser. For ArI measurements, the laser pumps the metastable ((2)P(0)3/2)4s level to the ((2)P(0)1/2)4p level using 696.7352 nm light, and fluorescence radiation from decay to the ((2)P(0)1/2)4s level at 772.6333 nm is observed...
November 2016: Review of Scientific Instruments
J Huang, W W Heidbrink, M G von Hellermann, L Stagner, C R Wu, Y M Hou, J F Chang, S Y Ding, Y J Chen, Y B Zhu, Z Jin, Z Xu, W Gao, J F Wang, B Lyu, Q Zang, G Q Zhong, L Hu, B Wan
To investigate the fast ion behavior, a fast ion D-alpha (FIDA) diagnostic system has been installed on EAST. Fast ion features can be inferred from the Doppler shifted spectrum of Balmer-alpha light from energetic hydrogenic atoms. This paper will focus on the validation of FIDA measurements performed using MHD-quiescent discharges in 2015 campaign. Two codes have been applied to calculate the Dα spectrum: one is a Monte Carlo code, Fortran 90 version FIDASIM, and the other is an analytical code, Simulation of Spectra (SOS)...
November 2016: Review of Scientific Instruments
X Y Peng, Z J Chen, X Zhang, T F Du, Z M Hu, L J Ge, Y M Zhang, J Q Sun, G Gorini, M Nocente, M Tardocchi, L Q Hu, G Q Zhong, N Pu, S Y Lin, B N Wan, X Q Li, G H Zhang, J X Chen, T S Fan
The 2.5 MeV TOFED (Time-Of-Flight Enhanced Diagnostics) neutron spectrometer with a double-ring structure has been installed at Experimental Advanced Superconducting Tokamak (EAST) to perform advanced neutron emission spectroscopy diagnosis of deuterium plasmas. This work describes the response function of the TOFED spectrometer, which is evaluated for the fully assembled instrument in its final layout. Results from Monte Carlo simulations and dedicated experiments with pulsed light sources are presented and used to determine properties of light transport from the scintillator...
November 2016: Review of Scientific Instruments
C Chrystal, K H Burrell, B A Grierson, S R Haskey, R J Groebner, D H Kaplan, A Briesemeister
The charge exchange recombination spectroscopy diagnostic on the DIII-D tokamak has been upgraded with the addition of more high radial resolution view chords near the edge of the plasma (r/a > 0.8). The additional views are diagnosed with the same number of spectrometers by placing fiber optics side-by-side at the spectrometer entrance with a precise separation that avoids wavelength shifted crosstalk without the use of bandpass filters. The new views improve measurement of edge impurity parameters in steep gradient, H-mode plasmas with many different shapes...
November 2016: Review of Scientific Instruments
D J Schlossberg, G M Bodner, M W Bongard, R J Fonck, J A Reusch, C Rodriguez Sanchez
A novel, cost-effective, multi-point Thomson scattering system has been designed, implemented, and operated on the Pegasus Toroidal Experiment. Leveraging advances in Nd:YAG lasers, high-efficiency volume phase holographic transmission gratings, and increased quantum-efficiency Generation 3 image-intensified charge coupled device (ICCD) cameras, the system provides Thomson spectra at eight spatial locations for a single grating/camera pair. The on-board digitization of the ICCD camera enables easy modular expansion, evidenced by recent extension from 4 to 12 plasma/background spatial location pairs...
November 2016: Review of Scientific Instruments
N Hell, P Beiersdorfer, E W Magee, G V Brown
We report the calibration of the Orion High-Resolution X-ray (OHREX) imaging crystal spectrometer at the EBIT-I electron beam ion trap at Livermore. Two such instruments, dubbed OHREX-1 and OHREX-2, are fielded for plasma diagnostics at the Orion laser facility in the United Kingdom. The OHREX spectrometer can simultaneously house two spherically bent crystals with a radius of curvature of r = 67.2 cm. The focusing properties of the spectrometer allow both for larger distance to the source due to the increase in collected light and for observation of extended sources...
November 2016: Review of Scientific Instruments
W C Young, D Parfeniuk
This paper provides an overview of the Thomson scattering diagnostic in use at General Fusion, including recent upgrades and upcoming plans. The plasma experiment under examination produces temperatures in the 50-500 eV range with density on the order of 10(20) m(-3). A four spatial point collection optics scheme has been implemented, with plans to expand to six spatial points. Recent changes to the optics of the laser beamline have reduced stray light. The system employs a frequency doubled Nd:YAG laser (532 nm), a grating spectrometer, and a photomultiplier array based detector...
November 2016: Review of Scientific Instruments
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