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Funaba H, Yasuhara R, Uehara H, Yamada I, Sakamoto R, Osakabe M, Den Hartog DJ. Electron temperature and density measurement by Thomson scattering with a high repetition rate laser of 20 kHz on LHD. Sci Rep 2022; 12:15112. [PMID: 36068266 PMCID: PMC9448754 DOI: 10.1038/s41598-022-19328-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2022] [Accepted: 08/29/2022] [Indexed: 11/30/2022] Open
Abstract
Thomson scattering measurements with a high-repetition-rate laser have commenced in the Large Helical Device. As an example of the fast phenomena captured by this diagnostic system, measurements at a 20 kHz repetition-rate in hydrogen pellet-injected plasmas are presented. Signal processing methods for this measurement have been developed and electron temperature profiles with almost 70 spatial points were evaluated at time intervals of 50 [Formula: see text]s. After Raman scattering calibration, electron density profiles were derived. Fast changes in the electron temperature and density profiles within 1 ms were observed.
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Affiliation(s)
- H Funaba
- National Institute for Fusion Science, National Institutes of Natural Sciences, Toki, Gifu, 509-5292, Japan.
| | - R Yasuhara
- National Institute for Fusion Science, National Institutes of Natural Sciences, Toki, Gifu, 509-5292, Japan.
| | - H Uehara
- National Institute for Fusion Science, National Institutes of Natural Sciences, Toki, Gifu, 509-5292, Japan
| | - I Yamada
- National Institute for Fusion Science, National Institutes of Natural Sciences, Toki, Gifu, 509-5292, Japan
| | - R Sakamoto
- National Institute for Fusion Science, National Institutes of Natural Sciences, Toki, Gifu, 509-5292, Japan
| | - M Osakabe
- National Institute for Fusion Science, National Institutes of Natural Sciences, Toki, Gifu, 509-5292, Japan
| | - D J Den Hartog
- Department of Physics, University of Wisconsin-Madison, Madison, WI, 53706-1390, USA
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Salzmann H, Nielsen P, Gowers C. Digital single-photon-avalanche-diode arrays for time-of-flight Thomson scattering diagnostics. Rev Sci Instrum 2022; 93:083517. [PMID: 36050083 DOI: 10.1063/5.0095252] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/09/2022] [Accepted: 07/15/2022] [Indexed: 06/15/2023]
Abstract
The collection optics of Thomson scattering systems for plasma devices are designed with maximum possible étendue to keep the required laser energy low. If the spatial resolution along the laser beam is performed by a time-of-flight method, then the detectors, in addition to a large sensitive area, must offer a high frequency bandwidth. Up until now, only microchannel-plate photomultipliers meet these requirements. Here, we investigate the potential use of digital avalanche photodiode arrays operated in the Geiger mode as alternative detectors. In this mode of operation, each array will serve as a fast, sensitive detector. The use of these detectors will lead to significant improvements of the Thomson scattering diagnostic. Most important of these will be a better spatial resolution, down to about 2 cm without deconvolution. Furthermore, the lifetime of the detectors will be increased; the detectors will cover the whole blue wing of the scattered spectrum when using a single wavelength laser, and this will enable measurements of electron temperature and density profiles at kHz repetition rates.
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Affiliation(s)
| | | | - Chris Gowers
- 27 Cavendish Rd., Matlock DE4 3GY, United Kingdom
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Zhai K, Schindler T, Ottaviano A, Zhang H, Fallah D, Wells J, Parke E, Thompson MC. Thomson scattering systems on C-2W field-reversed configuration plasma experiment. Rev Sci Instrum 2018; 89:10C118. [PMID: 30399708 DOI: 10.1063/1.5037327] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/23/2018] [Accepted: 09/14/2018] [Indexed: 06/08/2023]
Abstract
TAE Technologies' newly constructed C-2W experiment aims to improve the ion and electron temperatures in a sustained field-reversed configuration plasma. A suite of Thomson scattering systems has been designed and constructed for electron temperature and density profile measurements. The systems are designed for electron densities of 1 × 1012 cm-3 to 2 × 1014 cm-3 and temperature ranges from 10 eV to 2 keV. The central system will provide profile measurements of Te and ne at 16 radial locations from r = -9 cm to r = 64 cm with a temporal resolution of 20 kHz for 4 pulses or 1 kHz for 30 pulses. The jet system will provide profile measurements of Te and ne at 5 radial locations in the open field region from r = -5 cm to r = 15 cm with a temporal resolution of 100 Hz. The central system and its components have been characterized, calibrated, installed, and commissioned. A maximum-likelihood algorithm has been applied for data processing and analysis.
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Affiliation(s)
- K Zhai
- TAE Technologies, Inc., Foothill Ranch, California 92610, USA
| | - T Schindler
- TAE Technologies, Inc., Foothill Ranch, California 92610, USA
| | - A Ottaviano
- TAE Technologies, Inc., Foothill Ranch, California 92610, USA
| | - H Zhang
- TAE Technologies, Inc., Foothill Ranch, California 92610, USA
| | - D Fallah
- TAE Technologies, Inc., Foothill Ranch, California 92610, USA
| | - J Wells
- TAE Technologies, Inc., Foothill Ranch, California 92610, USA
| | - E Parke
- TAE Technologies, Inc., Foothill Ranch, California 92610, USA
| | - M C Thompson
- TAE Technologies, Inc., Foothill Ranch, California 92610, USA
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Fridström R, Chapman BE, Almagri AF, Frassinetti L, Brunsell PR, Nishizawa T, Sarff JS. Dependence of Perpendicular Viscosity on Magnetic Fluctuations in a Stochastic Topology. Phys Rev Lett 2018; 120:225002. [PMID: 29906181 DOI: 10.1103/physrevlett.120.225002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/05/2017] [Revised: 03/21/2018] [Indexed: 06/08/2023]
Abstract
In a magnetically confined plasma with a stochastic magnetic field, the dependence of the perpendicular viscosity on the magnetic fluctuation amplitude is measured for the first time. With a controlled, ∼ tenfold variation in the fluctuation amplitude, the viscosity increases ∼100-fold, exhibiting the same fluctuation-amplitude-squared dependence as the predicted rate of stochastic field line diffusion. The absolute value of the viscosity is well predicted by a model based on momentum transport in a stochastic field, the first in-depth test of this model.
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Affiliation(s)
- R Fridström
- Department of Fusion Plasma Physics, School of Electrical Engineering, KTH Royal Institute of Technology, SE-10044 Stockholm, Sweden
| | - B E Chapman
- Department of Physics, University of Wisconsin-Madison, 1150 University Avenue, Madison, Wisconsin 53706, USA
| | - A F Almagri
- Department of Physics, University of Wisconsin-Madison, 1150 University Avenue, Madison, Wisconsin 53706, USA
| | - L Frassinetti
- Department of Fusion Plasma Physics, School of Electrical Engineering, KTH Royal Institute of Technology, SE-10044 Stockholm, Sweden
| | - P R Brunsell
- Department of Fusion Plasma Physics, School of Electrical Engineering, KTH Royal Institute of Technology, SE-10044 Stockholm, Sweden
| | - T Nishizawa
- Department of Physics, University of Wisconsin-Madison, 1150 University Avenue, Madison, Wisconsin 53706, USA
| | - J S Sarff
- Department of Physics, University of Wisconsin-Madison, 1150 University Avenue, Madison, Wisconsin 53706, USA
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Young WC, Den Hartog DJ. Operation and beam profiling of an up to 200 kHz pulse-burst laser for Thomson scattering. Rev Sci Instrum 2014; 85:11D808. [PMID: 25430221 DOI: 10.1063/1.4885539] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
A new, high-repetition rate laser is in development for use on the Thomson scattering diagnostic on the Madison Symmetric Torus. The laser has been tested at a rate of 200 kHz in a pulse-burst operation, producing bursts of 5 pulses above 1.5 J each, while capable of bursts of 17 pulses at 100 kHz. A master oscillator-power amplifier architecture is used with a Nd:YVO4 oscillator, four Nd:YAG amplifiers, and a Nd:glass amplifier. A radial profile over the pulse sequence is measured by using a set of graphite apertures and an energy meter, showing a change in beam quality over a pulsing sequence.
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Affiliation(s)
- W C Young
- Department of Physics, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - D J Den Hartog
- Department of Physics, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
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Den Hartog DJ, Ambuel JR, Borchardt MT, Caspary KJ, Hartog EAD, Falkowski AF, Harris WS, Ko J, Pablant NA, Reusch JA, Robl PE, Stephens HD, Summers HP, Yang YM. Advances in Time-Resolved Measurement of Magnetic Field and Electron Temperature in Low-Magnetic-Field Plasmas. Fusion Science and Technology 2011. [DOI: 10.13182/fst11-a11589] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- D. J. Den Hartog
- University of Wisconsin–Madison, Madison, WI 53706 USA
- Center for Magnetic Self-Organization in Laboratory and Astrophysical Plasmas
| | - J. R. Ambuel
- University of Wisconsin–Madison, Madison, WI 53706 USA
| | | | - K. J. Caspary
- University of Wisconsin–Madison, Madison, WI 53706 USA
| | | | | | - W. S. Harris
- University of Wisconsin–Madison, Madison, WI 53706 USA
| | - J. Ko
- University of Wisconsin–Madison, Madison, WI 53706 USA
| | - N. A. Pablant
- University of California–San Diego, La Jolla, CA 92093 USA
| | - J. A. Reusch
- University of Wisconsin–Madison, Madison, WI 53706 USA
| | - P. E. Robl
- University of Wisconsin–Madison, Madison, WI 53706 USA
| | | | | | - Y. M. Yang
- University of Wisconsin–Madison, Madison, WI 53706 USA
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