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Three-dimensional nonlinear mode coupling of the double-tearing instability

Published online by Cambridge University Press:  01 August 1997

X. H. DENG
Affiliation:
Department of Space Physics, Wuhan University, Wuhan, 430072, People's Republic of China
J. F. WANG
Affiliation:
Department of Space Physics, Wuhan University, Wuhan, 430072, People's Republic of China
B. C. ZHANG
Affiliation:
Department of Space Physics, Wuhan University, Wuhan, 430072, People's Republic of China
Z. G. CHEN
Affiliation:
Department of Space Physics, Wuhan University, Wuhan, 430072, People's Republic of China

Abstract

The nonlinear development of the double-tearing instability and the mode coupling of different helicities are investigated numerically in cylindrical geometry. The results show that double-tearing instability arises with a central-hollow current-density profile, and the coupling of different low-poloidal mode numbers m leads to rapid destabilization of modes with higher poloidal mode numbers. This instability ultimately leads to the resistive reconnection of parts of the fluxes and reduces the current gradient in the unstable region. It seems likely that this process would accelerate current penetration in the tokamak start-up phase, and it also possibly plays an important role in the triggering of solar flares.

Type
Research Article
Copyright
1997 Cambridge University Press

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