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Review of Scientific Instruments

J P Holder, N Izumi, M Beach, M J Ayers, P Bell, M Schneider, D K Bradley, T Kohut, R Ehrlich, M Cohen, R Ramirez, D Thorn
At the National Ignition Facility (NIF), storage phosphor image plates (IP) are used extensively for recording x-rays, charged particles, and neutrons. For x-ray imaging and spectroscopy, absolute and relative calibrations are important for extracting plasma information from the diagnostics. We use Fuji MS, SR, and TR image plates that have been cut to fit custom diagnostic envelopes. The image plates are scanned on a General Electric FLA 7000 IP flying spot scanner. Calibrations for sensitivity, spatial scale, and temperature dependent fade are applied...
October 2018: Review of Scientific Instruments
Marcin Jakubowski, Peter Drewelow, Joris Fellinger, Aleix Puig Sitjes, Glen Wurden, Adnan Ali, Christoph Biedermann, Barbara Cannas, Didier Chauvin, Marc Gamradt, Henry Greve, Yu Gao, Dag Hathiramani, Ralf König, Axel Lorenz, Victor Moncada, Holger Niemann, Tran Thanh Ngo, Fabio Pisano, Thomas Sunn Pedersen
Wendelstein 7-X aims at quasi-steady state operation with up to 10 MW of heating power for 30 min. Power exhaust will be handled predominantly via 10 actively water cooled CFC (carbon-fiber-reinforced carbon) based divertor units designed to withstand power loads of 10 MW/m2 locally in steady state. If local loads exceed this value, a risk of local delamination of the CFC and failure of entire divertor modules arises. Infrared endoscopes to monitor all main plasma facing components are being prepared, and near real time software tools are under development to identify areas of excessive temperature rise, to distinguish them from non-critical events, and to trigger alarms...
October 2018: Review of Scientific Instruments
A Dal Molin, L Martinelli, M Nocente, D Rigamonti, A Abba, L Giacomelli, G Gorini, A Lvovskiy, A Muraro, M Tardocchi
A new compact gamma-ray spectrometer was developed in order to optimise the measurement of bremsstrahlung radiation emitted from runaway electrons in the MeV range. The detector is based on a cerium doped lutetium-yttrium oxyorthosilicate (LYSO:Ce) scintillator coupled to a silicon photomultiplier and is insensitive to magnetic fields. A dedicated electronic board was developed to optimise the signal readout as well as for online control of the device. The detector combines a dynamic range up to 10 MeV with moderate energy non-linearity, counting rate capabilities in excess of 1 MHz, and an energy resolution that extrapolates to a few % in the MeV range, thus meeting the requirements for its application to runaway electron studies by bremsstrahlung measurements in the gamma-ray energy range...
October 2018: Review of Scientific Instruments
P J Fimognari, T P Crowley, D R Demers, T D Kile
We have developed an ion current measurement instrument with a direct view of a plasma that reduces the particle and radiation-induced noise current it detects by over three orders of magnitude, from tens of microamps to tens of nanoamps. This is accomplished using electric fields, magnetic fields, and physical shielding that limit the flux of particles and radiation into the instrument and suppress the secondary electrons produced within it by particle and radiation impact. Operation of this detector in various configurations, without an ion beam, has allowed identification of the sources of noise current...
October 2018: Review of Scientific Instruments
Wenbin Liu, Yi Tan, Zhe Gao, Song Chai, Seulchan Hong
High current regulations are widely required in tokamaks to generate a specific magnetic field for plasma confinement which is challenging for power electronics. For high current regulation, 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 supply based on a buck converter for high current regulation in an inductive load is described, in which insulated gate bipolar transistors are used as switches and two capacitor banks are used for energy storage...
October 2018: Review of Scientific Instruments
B Marcinkevicius, A Hjalmarsson, E Andersson Sundén, G Ericsson
The Thin foil Proton Recoil (TPR) technique has previously been used for deuterium-tritium fusion neutron diagnostics [N. P. Hawkes et al. , Rev. Sci. Instrum. 70 , 1134 (1999)] and is one of the candidates put forward for use in ITER as part of the high resolution neutron spectrometer (HRNS) system [E. A. Sundén et al. , Nucl. Instrum. Methods Phys. Res., Sect. A 701 , 62 (2013)]. For ITER, the neutron spectrometer's main purposes are to determine the fuel ion density ratio as well as the ion temperature in DT plasma...
October 2018: Review of Scientific Instruments
M Nations, D Gupta, N Bolte, M C Thompson
In C-2W, an elevated impurity concentration can lead to significant degradation of plasma performance and energy losses through radiation. To gauge plasma contamination from impurities, the effective ion charge ( Z eff ) can be determined from measurements of bremsstrahlung continuum radiation over a small spectral range free from line radiation. To this end, a diagnostic system including visible and near-infrared bremsstrahlung detectors was deployed in C-2W to measure time-dependent radial distributions of Z eff ...
October 2018: Review of Scientific Instruments
M Beall, D Sheftman
Characterization of the plasma structure and density is critical for the diagnosis and control of C-2W plasma equilibria. To this end, two compact, highly portable, turnkey second harmonic interferometers are used to make measurements with greater flexibility than available from other diagnostics, providing important information in areas otherwise inaccessible to more complicated systems. The systems are based on a fiber-coupled 1064 nm Nd:YAG laser and provide a sensitivity of a few 1018 m-2 with a time resolution of a few microseconds...
October 2018: Review of Scientific Instruments
K-X Sun, M Valles, H Valencia, R O Nelson
Inertial Confinement Fusion (ICF) is undergoing more detailed research to increase neutron yield and will require high resolution imaging near the target. Neutron damage to diagnostics remains a serious issue in understanding and achieving ICF. We have demonstrated that Gallium Nitride (GaN) optoelectronic devices have exceptional neutron radiation hardness, by systematic testing of neutron radiation effects in GaN devices and materials with elevated neutron fluence levels and a broad neutron energy spectrum...
October 2018: Review of Scientific Instruments
Kunihiro Ogawa, Mitsutaka Isobe, Takeo Nishitani, Eiji Takada, Hiroki Kawase, Tatsuki Amitani, Neng Pu, Jungmin Jo, MunSeong Cheon, Junghee Kim, Misako Miwa, Shigeo Matsuyama, Isao Murata
The behavior of the 1 MeV triton has been studied in order to understand the alpha particle confinement property in the deuterium operation of toroidal fusion devices. To obtain time evolution of the deuterium-tritium (D-T) neutron emission rate where the secondary DT neutron emission rate is approximately 1012 n/s, we designed two high detection efficiency scintillating fiber (Sci-Fi) detectors: a 1 mm-diameter scintillation fiber-based detector Sci-Fi1 and a 2 mm-diameter scintillation fiber-based detector Sci-Fi2...
October 2018: Review of Scientific Instruments
Ryuichi Sano, Masakatsu Fukumoto, Tomohide Nakano, Naoyuki Oyama
A field of view (FoV) of the resistive bolometer systems specialized for the total radiated power analysis has been designed with bolometer systems having multiple-apertures in JT-60SA. The multi-aperture bolometer system can reduce the required number of bolometer channels for the determination of the total radiated power. The FoV design has been carried out to minimize unobserved and overlapping regions with the following requirements: (i) independent determination of the divertor and the main plasma radiation, (ii) limitation of the use of only three diagnostic ports, and (iii) a redundant FoV design...
October 2018: Review of Scientific Instruments
M Bassan, R Huxford, B Crowther, R Scannell, G Vayakis, M Walsh
In the ITER Core Plasma Thomson Scattering, the scattered light collection optics system is installed both inside and outside the diagnostic port under vacuum. The length of the optical path (∼6 m) and the need to shield the neutron and γ radiation increased the complexity of the system with the inclusion of multiple dog-legs, forcing the use of many elements with optical power. Multiple rounds of design have been required in order to satisfy iteratively the system requirements in terms of resolution, aberration, and shielding...
October 2018: Review of Scientific Instruments
Sophia V R Rocco, Jacob T Banasek, William M Potter, David A Hammer
A 526.5 nm Thomson scattering diagnostic laser enables probing of the plasma conditions of neon gas-puff z-pinch implosions with temporal resolution. Splitting the laser into two 2.5 J pulses, both 2.3 ns in duration and separated by 4 ns, allows observation of sub-nanosecond time-resolved spectra for a total time of 7 ns. Collection optics were set at 90° and 30° to the laser, observing the same on-axis scattering volume with a radial extent of 0.4 mm. The spectra from both angles were collected by using the same streak camera, using a coupling system that allowed us to obtain temporal, spectral, and angular resolution in the same image...
October 2018: Review of Scientific Instruments
B A Grierson, K H Burrell, C Chrystal, S R Haskey
A new calibration method for the DIII-D charge-exchange spectroscopy system produces a smoother impurity density profile compared to previous techniques, improving the accuracy of the impurity density profile reconstruction. The relative intensity calibration between the chords of the DIII-D charge-exchange recombination spectroscopy system is performed by firing neutral beams into the evacuated vacuum vessel pre-filled with neutral gas. Relative calibration is required in order to account for uncertainty in the 3D geometry of the neutral beam...
October 2018: Review of Scientific Instruments
Zhe Zhang, Wenbin Li, Qiushi Huang, Zhong Zhang, Shengzhen Yi, Liuyang Pan, Chun Xie, Przemyslaw Wachulak, Henryk Fiedorowicz, Zhanshan Wang
For investigating extreme ultraviolet (EUV) damage on optics, a table-top EUV focusing optical system was developed in the laboratory. Based on a modified Schwarzschild objective with a large numerical aperture and a laser-plasma light source, this optical system can generate a focusing spot with the maximum energy density of 2.27 J/cm2 at the focal plane of the objective at the wavelength of 13.5 nm. The structures and the characterized properties of this optical system are presented in this paper. For testing the performance of this setup, single-shot EUV damage tests were carried out on an optical substrate of CaF2 and a gold thin film...
October 2018: Review of Scientific Instruments
J Gonzalez-Martin, J Ayllon-Guerola, M Garcia-Munoz, A Herrmann, P Leitenstern, P De Marne, S Zoletnik, A Kovacsik, J Galdon-Quiroga, J Rivero-Rodriguez, M Rodriguez-Ramos, L Sanchis-Sanchez, J Dominguez
A new reciprocating scintillator based fast-ion loss detector has been installed a few centimeters above the outer divertor of the ASDEX Upgrade tokamak and between two of its lower Edge Localized Modes (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...
October 2018: Review of Scientific Instruments
D Sheftman, L Schmitz, D Gupta, M C Thompson
Accurate operation and high performance of the open field line plasma surrounding the field reversed configuration 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...
October 2018: Review of Scientific Instruments
Y Arikawa, S Matsubara, H Kishimoto, Y Abe, S Sakata, A Morace, R Mizutani, J Nishibata, A Yogo, M Nakai, H Shiraga, H Nishimura, S Fujioka, R Kodama
A large-aperture high-sensitivity image intensifier panel that consists of an avalanche photodiode array and a light-emitting diode array is presented. The device has 40% quantum efficiency, over 104 optical gain, and 80-ns time resolution. The aperture size of the device is 20 cm, and with the current manufacturing process, it can be scaled to arbitrarily larger sizes. The device can intensify the light from a single particle scintillation emission to an eye-visible bright flash. The image resolution of the device is currently limited by the size of the avalanche photodiode that is 2 mm, although it can be scaled to smaller sizes in the near future...
October 2018: Review of Scientific Instruments
Mingbiao Yu, Tijing Cai
No abstract text is available yet for this article.
October 2018: Review of Scientific Instruments
E P Hartouni, B Beeman, M J Eckart, G P Grim, R Hatarik, A S Moore, M Rubery, D Sayre, D J Schlossberg, C Waltz
Cherenkov radiators deployed to measure the neutron time-of-flight spectrum have response times associated with the neutron transit across the detector and are free from long time response tails characteristic of scintillation detectors. The Cherenkov radiation results from simple physical processes which makes them amenable to high fidelity Monte Carlo simulation. The instrument response function of neutron time-of-flight systems is a major contributor to both the systematic and statistical uncertainties of the parameters used to describe these spectra; in particular, the first and second moments of these distributions are associated with arrival time, t0 , and ion temperature, Tion ...
October 2018: Review of Scientific Instruments
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