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Title: The large-s field-reversed configuration experiment

Abstract

The Large-s Experiment (LSX) was built to study the formation and equilibrium properties of field-reversed configurations (FRCs) as the scale size increases. The dynamic, field-reversed theta-pinch method of FRC creation produces axial and azimuthal deformations and makes formation difficult, especially in large devices with large s (number of internal gyroradii) where it is difficult to achieve initial plasma uniformity. However, with the proper technique, these formation distortions can be minimized and are then observed to decay with time. This suggests that the basic stability and robustness of FRCs formed, and in some cases translated, in smaller devices may also characterize larger FRCs. Elaborate formation controls were included on LSX to provide the initial uniformity and symmetry necessary to minimize formation disturbances, and stable FRCs could be formed up to the design goal of s = 8. For x [le] 4, the formation distortions decayed away completely, resulting in symmetric equilibrium FRCs with record confinement times up to 0.5 ms, agreeing with previous empirical scaling laws ([tau][proportional to]sR). Above s = 4, reasonably long-lived (up to 0.3 ms) configurations could still be formed, but the initial formation distortions were so large that they never completely decayed away, and the equilibrium confinementmore » was degraded from the empirical expectations. The LSX was only operational for 1 yr, and it is not known whether s = 4 represents a fundamental limit for good confinement in simple (no ion beam stabilization) FRCs or whether it simply reflects a limit of present formation technology. Ideally, s could be increased through flux buildup from neutral beams. Since the addition of kinetic or beam ions will probably be desirable for heating, sustainment, and further stabilization of magnetohydrodynamic modes at reactor-level s values, neutral beam injection is the next logical step in FRC development. 24 refs., 21 figs., 2 tabs.« less

Authors:
; ; ; ; ; ; ; ;  [1]; ;  [2]
  1. STI Optronics, Bellevue, WA (United States)
  2. Univ. of Washington, Seattle (United States)
Publication Date:
OSTI Identifier:
6514222
Resource Type:
Journal Article
Journal Name:
Fusion Technology; (United States)
Additional Journal Information:
Journal Volume: 23:2; Journal ID: ISSN 0748-1896
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; COMPACT TORUS; EQUILIBRIUM; PLASMA PRODUCTION; FIELD-REVERSED THETA PINCH DEVICES; MAGNETIC CONFINEMENT; SCALING LAWS; STABILIZATION; CLOSED PLASMA DEVICES; CONFINEMENT; PINCH DEVICES; PLASMA CONFINEMENT; THERMONUCLEAR DEVICES; TORI; 700310* - Plasma Confinement- (1992-)

Citation Formats

Hoffman, A L, Carey, L N, Crawford, E A, Harding, D G, DeHart, T E, McDonald, K F, McNeil, J L, Milroy, R D, Slough, J T, Maqueda, R, and Wurden, G A. The large-s field-reversed configuration experiment. United States: N. p., 1993. Web.
Hoffman, A L, Carey, L N, Crawford, E A, Harding, D G, DeHart, T E, McDonald, K F, McNeil, J L, Milroy, R D, Slough, J T, Maqueda, R, & Wurden, G A. The large-s field-reversed configuration experiment. United States.
Hoffman, A L, Carey, L N, Crawford, E A, Harding, D G, DeHart, T E, McDonald, K F, McNeil, J L, Milroy, R D, Slough, J T, Maqueda, R, and Wurden, G A. 1993. "The large-s field-reversed configuration experiment". United States.
@article{osti_6514222,
title = {The large-s field-reversed configuration experiment},
author = {Hoffman, A L and Carey, L N and Crawford, E A and Harding, D G and DeHart, T E and McDonald, K F and McNeil, J L and Milroy, R D and Slough, J T and Maqueda, R and Wurden, G A},
abstractNote = {The Large-s Experiment (LSX) was built to study the formation and equilibrium properties of field-reversed configurations (FRCs) as the scale size increases. The dynamic, field-reversed theta-pinch method of FRC creation produces axial and azimuthal deformations and makes formation difficult, especially in large devices with large s (number of internal gyroradii) where it is difficult to achieve initial plasma uniformity. However, with the proper technique, these formation distortions can be minimized and are then observed to decay with time. This suggests that the basic stability and robustness of FRCs formed, and in some cases translated, in smaller devices may also characterize larger FRCs. Elaborate formation controls were included on LSX to provide the initial uniformity and symmetry necessary to minimize formation disturbances, and stable FRCs could be formed up to the design goal of s = 8. For x [le] 4, the formation distortions decayed away completely, resulting in symmetric equilibrium FRCs with record confinement times up to 0.5 ms, agreeing with previous empirical scaling laws ([tau][proportional to]sR). Above s = 4, reasonably long-lived (up to 0.3 ms) configurations could still be formed, but the initial formation distortions were so large that they never completely decayed away, and the equilibrium confinement was degraded from the empirical expectations. The LSX was only operational for 1 yr, and it is not known whether s = 4 represents a fundamental limit for good confinement in simple (no ion beam stabilization) FRCs or whether it simply reflects a limit of present formation technology. Ideally, s could be increased through flux buildup from neutral beams. Since the addition of kinetic or beam ions will probably be desirable for heating, sustainment, and further stabilization of magnetohydrodynamic modes at reactor-level s values, neutral beam injection is the next logical step in FRC development. 24 refs., 21 figs., 2 tabs.},
doi = {},
url = {https://www.osti.gov/biblio/6514222}, journal = {Fusion Technology; (United States)},
issn = {0748-1896},
number = ,
volume = 23:2,
place = {United States},
year = {1993},
month = {3}
}