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Title: Observation of energetic electron confinement in a largely stochastic reversed-field pinch plasma

Abstract

Runaway electrons with energies >100 keV are observed with the appearance of an m=1 magnetic island in the core of otherwise stochastic Madison Symmetric Torus [Dexter et al., Fusion Technol. 19, 131 (1991)] reversed-field-pinch plasmas. The island is associated with the innermost resonant tearing mode, which is usually the largest in the m=1 spectrum. The island appears over a range of mode spectra, from those with a weakly dominant mode to those, referred to as quasi single helicity, with a strongly dominant mode. In a stochastic field, the rate of electron loss increases with electron parallel velocity. Hence, high-energy electrons imply a region of reduced stochasticity. The global energy confinement time is about the same as in plasmas without high-energy electrons or an island in the core. Hence, the region of reduced stochasticity must be localized. Within a numerical reconstruction of the magnetic field topology, high-energy electrons are substantially better confined inside the island, relative to the external region. Therefore, it is deduced that the island provides a region of reduced stochasticity and that the high-energy electrons are generated and well confined within this region.

Authors:
; ; ; ; ; ; ;  [1]; ; ; ;  [2]
  1. Department of Physics, University of Wisconsin-Madison, Madison, Wisconsin 53706 (United States)
  2. Consorzio RFX, Euratom-ENEA Association, Corso Stati Uniti, 4 35127 Padova (Italy)
Publication Date:
OSTI Identifier:
21344660
Resource Type:
Journal Article
Journal Name:
Physics of Plasmas
Additional Journal Information:
Journal Volume: 17; Journal Issue: 1; Other Information: DOI: 10.1063/1.3292658; (c) 2010 American Institute of Physics; Journal ID: ISSN 1070-664X
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; CONFINEMENT TIME; ELECTRON LOSS; MAGNETIC ISLANDS; PLASMA; PLASMA CONFINEMENT; REVERSE-FIELD PINCH; RUNAWAY ELECTRONS; STOCHASTIC PROCESSES; TAIL ELECTRONS; TEARING INSTABILITY; CONFINEMENT; ELECTRONS; ELEMENTARY PARTICLES; FERMIONS; INSTABILITY; LEPTONS; MAGNETIC FIELD CONFIGURATIONS; PINCH EFFECT; PLASMA INSTABILITY; PLASMA MACROINSTABILITIES

Citation Formats

Clayton, D J, Chapman, B E, O'Connell, R, Almagri, A F, Burke, D R, Forest, C B, Goetz, J A, Kaufman, M C, Bonomo, F, Franz, P, Gobbin, M, and Piovesan, P. Observation of energetic electron confinement in a largely stochastic reversed-field pinch plasma. United States: N. p., 2010. Web. doi:10.1063/1.3292658.
Clayton, D J, Chapman, B E, O'Connell, R, Almagri, A F, Burke, D R, Forest, C B, Goetz, J A, Kaufman, M C, Bonomo, F, Franz, P, Gobbin, M, & Piovesan, P. Observation of energetic electron confinement in a largely stochastic reversed-field pinch plasma. United States. https://doi.org/10.1063/1.3292658
Clayton, D J, Chapman, B E, O'Connell, R, Almagri, A F, Burke, D R, Forest, C B, Goetz, J A, Kaufman, M C, Bonomo, F, Franz, P, Gobbin, M, and Piovesan, P. 2010. "Observation of energetic electron confinement in a largely stochastic reversed-field pinch plasma". United States. https://doi.org/10.1063/1.3292658.
@article{osti_21344660,
title = {Observation of energetic electron confinement in a largely stochastic reversed-field pinch plasma},
author = {Clayton, D J and Chapman, B E and O'Connell, R and Almagri, A F and Burke, D R and Forest, C B and Goetz, J A and Kaufman, M C and Bonomo, F and Franz, P and Gobbin, M and Piovesan, P},
abstractNote = {Runaway electrons with energies >100 keV are observed with the appearance of an m=1 magnetic island in the core of otherwise stochastic Madison Symmetric Torus [Dexter et al., Fusion Technol. 19, 131 (1991)] reversed-field-pinch plasmas. The island is associated with the innermost resonant tearing mode, which is usually the largest in the m=1 spectrum. The island appears over a range of mode spectra, from those with a weakly dominant mode to those, referred to as quasi single helicity, with a strongly dominant mode. In a stochastic field, the rate of electron loss increases with electron parallel velocity. Hence, high-energy electrons imply a region of reduced stochasticity. The global energy confinement time is about the same as in plasmas without high-energy electrons or an island in the core. Hence, the region of reduced stochasticity must be localized. Within a numerical reconstruction of the magnetic field topology, high-energy electrons are substantially better confined inside the island, relative to the external region. Therefore, it is deduced that the island provides a region of reduced stochasticity and that the high-energy electrons are generated and well confined within this region.},
doi = {10.1063/1.3292658},
url = {https://www.osti.gov/biblio/21344660}, journal = {Physics of Plasmas},
issn = {1070-664X},
number = 1,
volume = 17,
place = {United States},
year = {Fri Jan 15 00:00:00 EST 2010},
month = {Fri Jan 15 00:00:00 EST 2010}
}