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Du XD, Hong RJ, Heidbrink WW, Jian X, Wang H, Eidietis NW, Van Zeeland MA, Austin ME, Liu Y, Crocker NA, Rhodes TL, Särkimäki K, Snicker A, Wu W, Knolker M. Multiscale Chirping Modes Driven by Thermal Ions in a Plasma with Reactor-Relevant Ion Temperature. Phys Rev Lett 2021; 127:025001. [PMID: 34296897 DOI: 10.1103/physrevlett.127.025001] [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: 02/04/2021] [Revised: 04/02/2021] [Accepted: 06/09/2021] [Indexed: 06/13/2023]
Abstract
A thermal ion driven bursting instability with rapid frequency chirping, considered as an Alfvénic ion temperature gradient mode, has been observed in plasmas having reactor-relevant temperature in the DIII-D tokamak. The modes are excited over a wide spatial range from macroscopic device size to microturbulence size and the perturbation energy propagates across multiple spatial scales. The radial mode structure is able to expand from local to global in ∼0.1 ms and it causes magnetic topology changes in the plasma edge, which can lead to a minor disruption event. Since the mode is typically observed in the high ion temperature ≳10 keV and high-β plasma regime, the manifestation of the mode in future reactors should be studied with development of mitigation strategies, if needed. This is the first observation of destabilization of the Alfvén continuum caused by the compressibility of ions with reactor-relevant ion temperature.
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Affiliation(s)
- X D Du
- General Atomics, P.O. Box 85608, San Diego, California 92186-5608, USA
| | - R J Hong
- University of California, Los Angeles, California 90095, USA
| | - W W Heidbrink
- University of California, Irvine, California 92697, USA
| | - X Jian
- University of California, San Diego, La Jolla, California 92093-0417, USA
| | - H Wang
- General Atomics, P.O. Box 85608, San Diego, California 92186-5608, USA
| | - N W Eidietis
- University of California, Los Angeles, California 90095, USA
| | - M A Van Zeeland
- General Atomics, P.O. Box 85608, San Diego, California 92186-5608, USA
| | - M E Austin
- University of Texas-Austin, Austin, Texas 78712, USA
| | - Y Liu
- General Atomics, P.O. Box 85608, San Diego, California 92186-5608, USA
| | - N A Crocker
- University of California, Los Angeles, California 90095, USA
| | - T L Rhodes
- University of California, Los Angeles, California 90095, USA
| | - K Särkimäki
- Department of Physics, Chalmers University of Technology, SE-41296 Göteborg, Sweden
| | - A Snicker
- Department of Applied Physics, Aalto University, P.O. Box 11100, 00076 AALTO, Espoo, Finland
| | - W Wu
- General Atomics, P.O. Box 85608, San Diego, California 92186-5608, USA
| | - M Knolker
- General Atomics, P.O. Box 85608, San Diego, California 92186-5608, USA
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Hollmann EM, Parks PB, Shiraki D, Alexander N, Eidietis NW, Lasnier CJ, Moyer RA. Demonstration of Tokamak Discharge Shutdown with Shell Pellet Payload Impurity Dispersal. Phys Rev Lett 2019; 122:065001. [PMID: 30822084 DOI: 10.1103/physrevlett.122.065001] [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: 12/11/2018] [Indexed: 06/09/2023]
Abstract
The first rapid tokamak discharge shutdown using dispersive core payload deposition with shell pellets has been achieved in the DIII-D tokamak. Shell pellets are being investigated as a possible new path toward achieving tokamak disruption mitigation with both low conducted wall heat loads and slow current quench. Conventional disruption mitigation injects radiating impurities into the outer edge of the tokamak plasma, which tends to result in poor impurity assimilation and creates a strong edge cooling and outward heat flow, thus requiring undesirable high-Z impurities to achieve low conducted heat loads. The shell pellet technique aims to produce a hollow temperature profile by using a thin, low-ablation shell surrounding a dispersive payload, giving a greatly increased impurity ablation (and radiation) rate when the payload is released in the plasma core. This principle was demonstrated successfully using 3.6 mm outer diameter, 40 μm thickness diamond shells holding boron powder. The pellets caused rapid (<10 ms) discharge shutdown with low conducted divertor heat fluence (∼0.1 MJ/m^{2}). Confirmation of massive release of the boron powder payload into the plasma core was obtained spectroscopically. Some evidence for the formation of a hollow temperature profile during the shutdown was observed. These first results open a new avenue for disruption mitigation research, hopefully enabling development of highly effective methods of avoiding disruption wall damage in future reactor-scale tokamaks.
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Affiliation(s)
- E M Hollmann
- University of California-San Diego, La Jolla, California 92093, USA
| | - P B Parks
- General Atomics, San Diego, California 92186, USA
| | - D Shiraki
- Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - N Alexander
- General Atomics, San Diego, California 92186, USA
| | - N W Eidietis
- General Atomics, San Diego, California 92186, USA
| | - C J Lasnier
- Lawrence Livermore National Laboratory, Livermore, California 94550, USA
| | - R A Moyer
- University of California-San Diego, La Jolla, California 92093, USA
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Paz-Soldan C, Cooper CM, Aleynikov P, Pace DC, Eidietis NW, Brennan DP, Granetz RS, Hollmann EM, Liu C, Lvovskiy A, Moyer RA, Shiraki D. Spatiotemporal Evolution of Runaway Electron Momentum Distributions in Tokamaks. Phys Rev Lett 2017; 118:255002. [PMID: 28696735 DOI: 10.1103/physrevlett.118.255002] [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] [Received: 01/31/2017] [Indexed: 06/07/2023]
Abstract
Novel spatial, temporal, and energetically resolved measurements of bremsstrahlung hard-x-ray (HXR) emission from runaway electron (RE) populations in tokamaks reveal nonmonotonic RE distribution functions whose properties depend on the interplay of electric field acceleration with collisional and synchrotron damping. Measurements are consistent with theoretical predictions of momentum-space attractors that accumulate runaway electrons. RE distribution functions are measured to shift to a higher energy when the synchrotron force is reduced by decreasing the toroidal magnetic field strength. Increasing the collisional damping by increasing the electron density (at a fixed magnetic and electric field) reduces the energy of the nonmonotonic feature and reduces the HXR growth rate at all energies. Higher-energy HXR growth rates extrapolate to zero at the expected threshold electric field for RE sustainment, while low-energy REs are anomalously lost. The compilation of HXR emission from different sight lines into the plasma yields energy and pitch-angle-resolved RE distributions and demonstrates increasing pitch-angle and radial gradients with energy.
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Affiliation(s)
- C Paz-Soldan
- General Atomics, San Diego, California 92186, USA
| | - C M Cooper
- Oak Ridge Associated Universities, Oak Ridge, Tennessee 37831, USA
| | - P Aleynikov
- Max-Planck Institute for Plasma Physics, Greifswald, Germany
| | - D C Pace
- General Atomics, San Diego, California 92186, USA
| | - N W Eidietis
- General Atomics, San Diego, California 92186, USA
| | - D P Brennan
- Princeton University, Princeton, New Jersey 05764, USA
| | - R S Granetz
- Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - E M Hollmann
- University of California-San Diego, La Jolla, California 92093, USA
| | - C Liu
- Princeton University, Princeton, New Jersey 05764, USA
| | - A Lvovskiy
- Oak Ridge Associated Universities, Oak Ridge, Tennessee 37831, USA
| | - R A Moyer
- University of California-San Diego, La Jolla, California 92093, USA
| | - D Shiraki
- Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
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Yang HL, Kwak JG, Oh YK, Park KR, Kim WC, Lee SG, Kim JY, Bae YS, Park YM, Kim HK, Chu Y, Park MK, Kim JS, In SR, Joung SH, Choe WH, Park HK, Hwang YS, Na YS, Park JG, Ahn JW, Park YS, Kwon M, Leuer JA, Eidietis NW, Hyatt AW, Walker M, Gorelov Y, Lohr J, Mueller D, Grisham LR, Sabbagh SA, Watanabe K, Inoue T, Sakamoto K, Oda Y, Kajiwara K, Ellis R, Hosea J, Delpech L, Hoang TT, Litaudon X, Namkung W, Cho MH. Overview of KSTAR Results in Phase-I Operation. Fusion Science and Technology 2017. [DOI: 10.13182/fst13-a19130] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [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)
- H. L. Yang
- National Fusion Research Institute, 113 Gwahangno, Yusung-Gu, Daejeon, 305-333, Korea
| | - J. G. Kwak
- National Fusion Research Institute, 113 Gwahangno, Yusung-Gu, Daejeon, 305-333, Korea
| | - Y. K. Oh
- National Fusion Research Institute, 113 Gwahangno, Yusung-Gu, Daejeon, 305-333, Korea
| | - K. R. Park
- National Fusion Research Institute, 113 Gwahangno, Yusung-Gu, Daejeon, 305-333, Korea
| | - W. C. Kim
- National Fusion Research Institute, 113 Gwahangno, Yusung-Gu, Daejeon, 305-333, Korea
| | - S. G. Lee
- National Fusion Research Institute, 113 Gwahangno, Yusung-Gu, Daejeon, 305-333, Korea
| | - J. Y. Kim
- National Fusion Research Institute, 113 Gwahangno, Yusung-Gu, Daejeon, 305-333, Korea
| | - Y. S. Bae
- National Fusion Research Institute, 113 Gwahangno, Yusung-Gu, Daejeon, 305-333, Korea
| | - Y. M. Park
- National Fusion Research Institute, 113 Gwahangno, Yusung-Gu, Daejeon, 305-333, Korea
| | - H. K. Kim
- National Fusion Research Institute, 113 Gwahangno, Yusung-Gu, Daejeon, 305-333, Korea
| | - Y. Chu
- National Fusion Research Institute, 113 Gwahangno, Yusung-Gu, Daejeon, 305-333, Korea
| | - M. K. Park
- National Fusion Research Institute, 113 Gwahangno, Yusung-Gu, Daejeon, 305-333, Korea
| | - J. S. Kim
- National Fusion Research Institute, 113 Gwahangno, Yusung-Gu, Daejeon, 305-333, Korea
| | - S. R. In
- Korea Atomic Energy Research Insititute, Daeduk-Daero 989-111, Yuseong-gu, Daejeon, 305-353, Korea
| | - S. H. Joung
- Korea Atomic Energy Research Insititute, Daeduk-Daero 989-111, Yuseong-gu, Daejeon, 305-353, Korea
| | - W. H. Choe
- Korea Advanced Institute of Science and Technology, 291 Daehak-ro, Yuseong-gu, Daejeon, 305-701, Korea
| | - H. K. Park
- Pohang Univ. of Science and Technology, 77 Cheongam-ro, Nam-gu, Pohang, Gyungbuk, 790-784, Korea
| | - Y. S. Hwang
- Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul, 151-742, Korea
| | - Y. S. Na
- Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul, 151-742, Korea
| | - J. G. Park
- Princeton Plasma Physics Lab., P.O. Box 451 Princetorn, NJ 08543-0451, USA
| | - J. W. Ahn
- Oak Ridge National Lab., 1 Bethal Valley Rd, OakRidge, TN37831, USA
| | - Y. S. Park
- Columbia Univ., James Forrestal Campus (EWA 244), P.O. Box 451, Princeton, NJ 08543, USA
| | - M. Kwon
- National Fusion Research Institute, 113 Gwahangno, Yusung-Gu, Daejeon, 305-333, Korea
| | - J. A. Leuer
- General Atomics, 3550 General Atomics Court, San Diego, CA 92121, USA
| | - N. W. Eidietis
- General Atomics, 3550 General Atomics Court, San Diego, CA 92121, USA
| | - A. W. Hyatt
- General Atomics, 3550 General Atomics Court, San Diego, CA 92121, USA
| | - M. Walker
- General Atomics, 3550 General Atomics Court, San Diego, CA 92121, USA
| | - Y. Gorelov
- General Atomics, 3550 General Atomics Court, San Diego, CA 92121, USA
| | - J. Lohr
- General Atomics, 3550 General Atomics Court, San Diego, CA 92121, USA
| | - D. Mueller
- Princeton Plasma Physics Lab., P.O. Box 451 Princetorn, NJ 08543-0451, USA
| | - L. R. Grisham
- Princeton Plasma Physics Lab., P.O. Box 451 Princetorn, NJ 08543-0451, USA
| | - S. A. Sabbagh
- Columbia Univ., James Forrestal Campus (EWA 244), P.O. Box 451, Princeton, NJ 08543, USA
| | - K. Watanabe
- Japan Atomic Energy Agency, 801-1 Mukoyama, Naka-city, Ibaraki-ken, 311-0193, Japan
| | - T. Inoue
- Japan Atomic Energy Agency, 801-1 Mukoyama, Naka-city, Ibaraki-ken, 311-0193, Japan
| | - K. Sakamoto
- Japan Atomic Energy Agency, 801-1 Mukoyama, Naka-city, Ibaraki-ken, 311-0193, Japan
| | - Y. Oda
- Japan Atomic Energy Agency, 801-1 Mukoyama, Naka-city, Ibaraki-ken, 311-0193, Japan
| | - K. Kajiwara
- Japan Atomic Energy Agency, 801-1 Mukoyama, Naka-city, Ibaraki-ken, 311-0193, Japan
| | - R. Ellis
- Princeton Plasma Physics Lab., P.O. Box 451 Princetorn, NJ 08543-0451, USA
| | - J. Hosea
- Princeton Plasma Physics Lab., P.O. Box 451 Princetorn, NJ 08543-0451, USA
| | - L. Delpech
- CEA, IFRM,13108 Saint-Paul-Lez-Durance, France
| | - T. T. Hoang
- CEA, IFRM,13108 Saint-Paul-Lez-Durance, France
| | - X. Litaudon
- CEA, IFRM,13108 Saint-Paul-Lez-Durance, France
| | - W. Namkung
- Pohang Univ. of Science and Technology, 77 Cheongam-ro, Nam-gu, Pohang, Gyungbuk, 790-784, Korea
| | - M. H. Cho
- Pohang Univ. of Science and Technology, 77 Cheongam-ro, Nam-gu, Pohang, Gyungbuk, 790-784, Korea
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Yoon SW, England AC, Kim WC, Yonekawa H, Bak JG, Park BH, Kim J, You KI, Jeon YM, Hahn SH, Oh YK, Chung J, Lee KD, Lee HJ, Leuer JA, Eidietis NW. Effect of Magnetic Materials on the In-Vessel Magnetic Configuration in KSTAR. Fusion Science and Technology 2017. [DOI: 10.13182/fst13-706] [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)
- S. W. Yoon
- National Fusion Research Institute, 113 Gwahangno, Yusung-Gu, Daejeon, 305-333, Korea
| | - A. C. England
- National Fusion Research Institute, 113 Gwahangno, Yusung-Gu, Daejeon, 305-333, Korea
| | - W. C. Kim
- National Fusion Research Institute, 113 Gwahangno, Yusung-Gu, Daejeon, 305-333, Korea
| | - H. Yonekawa
- National Fusion Research Institute, 113 Gwahangno, Yusung-Gu, Daejeon, 305-333, Korea
| | - J. G. Bak
- National Fusion Research Institute, 113 Gwahangno, Yusung-Gu, Daejeon, 305-333, Korea
| | - B. H. Park
- National Fusion Research Institute, 113 Gwahangno, Yusung-Gu, Daejeon, 305-333, Korea
| | - J. Kim
- National Fusion Research Institute, 113 Gwahangno, Yusung-Gu, Daejeon, 305-333, Korea
| | - K. I. You
- National Fusion Research Institute, 113 Gwahangno, Yusung-Gu, Daejeon, 305-333, Korea
| | - Y. M. Jeon
- National Fusion Research Institute, 113 Gwahangno, Yusung-Gu, Daejeon, 305-333, Korea
| | - S. H. Hahn
- National Fusion Research Institute, 113 Gwahangno, Yusung-Gu, Daejeon, 305-333, Korea
| | - Y. K. Oh
- National Fusion Research Institute, 113 Gwahangno, Yusung-Gu, Daejeon, 305-333, Korea
| | - J. Chung
- National Fusion Research Institute, 113 Gwahangno, Yusung-Gu, Daejeon, 305-333, Korea
| | - K. D. Lee
- National Fusion Research Institute, 113 Gwahangno, Yusung-Gu, Daejeon, 305-333, Korea
| | - H. J. Lee
- National Fusion Research Institute, 113 Gwahangno, Yusung-Gu, Daejeon, 305-333, Korea
| | - J. A. Leuer
- General Atomics, 3550 General Atomics Court, San Diego, California 92121
| | - N. W. Eidietis
- General Atomics, 3550 General Atomics Court, San Diego, California 92121
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Cooper CM, Pace DC, Paz-Soldan C, Commaux N, Eidietis NW, Hollmann EM, Shiraki D. Applying the new gamma ray imager diagnostic to measurements of runaway electron Bremsstrahlung radiation in the DIII-D Tokamak (invited). Rev Sci Instrum 2016; 87:11E602. [PMID: 27910457 DOI: 10.1063/1.4961288] [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: 06/06/2023]
Abstract
A new gamma ray imager (GRI) is developed to probe the electron distribution function with 2D spatial resolution during runaway electron (RE) experiments at the DIII-D tokamak. The diagnostic is sensitive to 0.5-100 MeV gamma rays, allowing characterization of the RE distribution function evolution during RE growth and dissipation. The GRI consists of a lead "pinhole camera" mounted on the DIII-D midplane with 123 honeycombed tangential chords 20 cm wide that span the vessel interior. Up to 30 bismuth germanate (BGO) scintillation detectors capture RE bremsstrahlung radiation for Pulse Height Analysis (PHA) capable of discriminating up to 20 000 pulses per second. Digital signal processing routines combining shaping filters are performed during PHA to reject noise and record gamma ray energy. The GRI setup and PHA algorithms will be described and initial data from experiments will be presented. A synthetic diagnostic is developed to generate the gamma ray spectrum of a GRI channel given the plasma information and a prescribed distribution function. Magnetic reconstructions of the plasma are used to calculate the angle between every GRI sightline and orient and discriminate gamma rays emitted by a field-aligned RE distribution function.
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Affiliation(s)
- C M Cooper
- Oak Ridge Associated Universities, Oak Ridge, Tennessee 37830, USA
| | - D C Pace
- General Atomics, P.O. Box 85608, San Diego, California 92186-5608, USA
| | - C Paz-Soldan
- General Atomics, P.O. Box 85608, San Diego, California 92186-5608, USA
| | - N Commaux
- Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830, USA
| | - N W Eidietis
- General Atomics, P.O. Box 85608, San Diego, California 92186-5608, USA
| | - E M Hollmann
- University of California, San Diego, La Jolla, California 92093-0533, USA
| | - D Shiraki
- Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830, USA
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Pace DC, Cooper CM, Taussig D, Eidietis NW, Hollmann EM, Riso V, Van Zeeland MA, Watkins M. Gamma ray imager on the DIII-D tokamak. Rev Sci Instrum 2016; 87:043507. [PMID: 27131674 DOI: 10.1063/1.4945566] [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: 01/25/2016] [Accepted: 03/24/2016] [Indexed: 06/05/2023]
Abstract
A gamma ray camera is built for the DIII-D tokamak [J. Luxon, Nucl. Fusion 42, 614 (2002)] that provides spatial localization and energy resolution of gamma flux by combining a lead pinhole camera with custom-built detectors and optimized viewing geometry. This diagnostic system is installed on the outer midplane of the tokamak such that its 123 collimated sightlines extend across the tokamak radius while also covering most of the vertical extent of the plasma volume. A set of 30 bismuth germanate detectors can be secured in any of the available sightlines, allowing for customizable coverage in experiments with runaway electrons in the energy range of 1-60 MeV. Commissioning of the gamma ray imager includes the quantification of electromagnetic noise sources in the tokamak machine hall and a measurement of the energy spectrum of background gamma radiation. First measurements of gamma rays coming from the plasma provide a suitable testbed for implementing pulse height analysis that provides the energy of detected gamma photons.
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Affiliation(s)
- D C Pace
- General Atomics, P.O. Box 85608, San Diego, California 92186-5608, USA
| | - C M Cooper
- Oak Ridge Associated Universities, Oak Ridge, Tennessee 37830, USA
| | - D Taussig
- General Atomics, P.O. Box 85608, San Diego, California 92186-5608, USA
| | - N W Eidietis
- General Atomics, P.O. Box 85608, San Diego, California 92186-5608, USA
| | - E M Hollmann
- University of California-San Diego, 9500 Gilman Dr., La Jolla, California 92093-0417, USA
| | - V Riso
- State University of New York-Buffalo, 12 Capen Hall, Buffalo, New York 14260-1660, USA
| | - M A Van Zeeland
- General Atomics, P.O. Box 85608, San Diego, California 92186-5608, USA
| | - M Watkins
- General Atomics, P.O. Box 85608, San Diego, California 92186-5608, USA
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Garstka GD, Unterberg EA, Battaglia DJ, Bongard MW, Eidietis NW, Fonck RJ, Frost MJ, McGarry MB, Sontag AC, Squires BJ, Winz GR. Attainment of High Normalized Current by Current Profile Manipulation in the Pegasus Toroidal Experiment. J Fusion Energ 2007. [DOI: 10.1007/s10894-007-9094-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Unterberg EA, Battaglia DJ, Bongard MW, Eidietis NW, Fonck RJ, Frost MJ, Garstka GD, Kujak-Ford BA, Lewicki BT, Squires BJ, Winz GR. Initial Experiments at High Normalized Current in the Pegasus Toroidal Experiment. J Fusion Energ 2006. [DOI: 10.1007/s10894-006-9056-z] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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