[Table of Contents]

Plasma and Fusion Research

Volume 8, 2403121 (2013)

Regular Articles

Stability of Double Tearing Mode in the Presence of Shear Flows
Mao AOHUA1,2), Li JIQUAN2), Yasuaki KISHIMOTO2) and Liu JINYUAN1)
1)
Dalian University of Technology, Dalian 116024, China
2)
Kyoto University, Uji 611-0011, Japan
(Received 20 November 2012 / Accepted 4 July 2013 / Published 26 September 2013)

Abstract

The stability of two eigen states of double tearing mode (DTM) with symmetric or antisymmetric islands in the presence of shear flows is numerically simulated based on a reduced MHD model in slab geometry. For given antisymmetric flow profile, a degenerated state is observed at a critical flow amplitude vc. Below vc, the shear flow stabilizes the DTM with antisymmetric islands and destabilizes the other one through distorting the magnetic flux mainly governed by the global effect of flow profile. Above vc, the degenerated state bifurcates into two eigen states with the same growth rate but opposed propagating direction. These two eigen modes show single tearing mode structure due to one of two islands is prevented by the Alfvén resonance (AR). However, the AR can destabilize the DTMs through enhancing the inflow to the X-point of the remaining island, then competing with the stabilization of local flow shear, leading to distinctive features of DTM eigen states.

Keywords

double tearing mode, reduced MHD, magnetic island, shear flow, Alfvén resonance

DOI: 10.1585/pfr.8.2403121

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This paper may be cited as follows:

Mao AOHUA, Li JIQUAN, Yasuaki KISHIMOTO and Liu JINYUAN, Plasma Fusion Res. 8, 2403121 (2013).