Stability of coupled tearing and twisting modes in tokamaks

Journal Article · Sat Oct 01 04:00:00 EDT 1994 · Physics of Plasmas; (United States)

DOI:https://doi.org/10.1063/1.870482· OSTI ID:6692884

Fitzpatrick, R ^[1]

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1. Institute for Fusion Studies, The University of Texas at Austin, Austin, Texas 78712 (United States)

A dispersion relation is derived for resistive modes of arbitrary parity in a tokamak plasma. At low mode amplitude, tearing and twisting modes which have nonideal magnetohydrodynamical (MHD) behavior at only one rational surface at a time in the plasma are decoupled via sheared rotation and diamagnetic flows. At higher amplitude, more unstable compound'' modes develop which have nonideal behavior simultaneously at many surfaces. Such modes possess tearing parity layers at some of the nonideal surfaces, and twisting parity layers at others, but mixed parity layers are generally disallowed. At low mode number, compound'' modes are likely to have tearing parity layers at all of the nonideal surfaces in a very low-[beta] plasma, but twisting parity layers become more probable as the plasma [beta] is increased. At high mode number, unstable twisting modes which exceed a critical amplitude drive conventional magnetic island chains on alternate rational surfaces, to form an interlocking structure in which the O points and X points of neighboring chains line up.

• OSTI ID: 6692884
• Journal Information: Physics of Plasmas; (United States), Journal Name: Physics of Plasmas; (United States) Vol. 1:10; ISSN PHPAEN; ISSN 1070-664X
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
700340* -- Plasma Waves
Oscillations
& Instabilities-- (1992-)
CLOSED PLASMA DEVICES
DISPERSION RELATIONS
FLUID MECHANICS
HYDRODYNAMICS
INSTABILITY
LOW-BETA PLASMA
MAGNETIC FIELD CONFIGURATIONS
MAGNETIC FLUX
MAGNETIC ISLANDS
MAGNETOHYDRODYNAMICS
MECHANICS
PLASMA
PLASMA INSTABILITY
PLASMA MACROINSTABILITIES
ROTATING PLASMA
TEARING INSTABILITY
THERMONUCLEAR DEVICES
TOKAMAK DEVICES