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Title: Nonlinear tearing mode interactions and mode locking in reversed-field pinches

Abstract

The nonlinear interaction of a set of tearing instabilities and plasma flow is studied in a cylindrical plasma. An analytic theory of mode locking is developed, which includes the effects of the localized electromagnetic torques, plasma inertia, and cross-field viscosity. The calculation is specialized for the case of mode locking on the Madison Symmetric Torus (MST) reversed-field pinch [R. N. Dexter {ital et} {ital al}., Fusion Technol. {bold 19}, 131 (1991)]. In MST plasmas, a set of {ital m}=1 tearing instabilities become phase locked and form a toroidally localized, rotating magnetic disturbance. An evolution equation for the phase velocity of this magnetic disturbance is derived that accounts for two types of electromagnetic torques. The external torques describe the interaction of the tearing modes with static magnetic perturbations located outside the plasma region. The interior torques describe the nonlinear interaction of three tearing modes that satisfy a wave number resonance condition. For conditions typical of MST, the internal torques dominate the external torques, which suggest the nonlinear interaction of tearing instabilities play a prominent role in the momentum degradation and mode locking. {copyright} {ital 1996 American Institute of Physics.}

Authors:
 [1]
  1. Departments of Nuclear Engineering and Engineering Physics and Physics, University of Wisconsin, Madison, Wisconsin 53706-1687 (United States)
Publication Date:
OSTI Identifier:
397523
DOE Contract Number:  
FG02-85ER53212; FG02-86ER53218
Resource Type:
Journal Article
Journal Name:
Physics of Plasmas
Additional Journal Information:
Journal Volume: 3; Journal Issue: 12; Other Information: PBD: Dec 1996
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION; REVERSE-FIELD PINCH; TEARING INSTABILITY; MODE LOCKING; PLASMA MACROINSTABILITIES; MAGNETOHYDRODYNAMICS; PHASE VELOCITY

Citation Formats

Hegna, C C. Nonlinear tearing mode interactions and mode locking in reversed-field pinches. United States: N. p., 1996. Web. doi:10.1063/1.872033.
Hegna, C C. Nonlinear tearing mode interactions and mode locking in reversed-field pinches. United States. doi:10.1063/1.872033.
Hegna, C C. Sun . "Nonlinear tearing mode interactions and mode locking in reversed-field pinches". United States. doi:10.1063/1.872033.
@article{osti_397523,
title = {Nonlinear tearing mode interactions and mode locking in reversed-field pinches},
author = {Hegna, C C},
abstractNote = {The nonlinear interaction of a set of tearing instabilities and plasma flow is studied in a cylindrical plasma. An analytic theory of mode locking is developed, which includes the effects of the localized electromagnetic torques, plasma inertia, and cross-field viscosity. The calculation is specialized for the case of mode locking on the Madison Symmetric Torus (MST) reversed-field pinch [R. N. Dexter {ital et} {ital al}., Fusion Technol. {bold 19}, 131 (1991)]. In MST plasmas, a set of {ital m}=1 tearing instabilities become phase locked and form a toroidally localized, rotating magnetic disturbance. An evolution equation for the phase velocity of this magnetic disturbance is derived that accounts for two types of electromagnetic torques. The external torques describe the interaction of the tearing modes with static magnetic perturbations located outside the plasma region. The interior torques describe the nonlinear interaction of three tearing modes that satisfy a wave number resonance condition. For conditions typical of MST, the internal torques dominate the external torques, which suggest the nonlinear interaction of tearing instabilities play a prominent role in the momentum degradation and mode locking. {copyright} {ital 1996 American Institute of Physics.}},
doi = {10.1063/1.872033},
journal = {Physics of Plasmas},
number = 12,
volume = 3,
place = {United States},
year = {1996},
month = {12}
}