Zonal flow dynamics in the double tearing mode with antisymmetric shear flows
Abstract
The generation dynamics and the structural characteristics of zonal flows are investigated in the double tearing mode (DTM) with antisymmetric shear flows. Two kinds of zonal flow oscillations are revealed based on reduced resistive magnetohydrodynamics simulations, which depend on the shear flow amplitudes corresponding to different DTM eigen mode states, elaborated by Mao et al. [Phys. Plasmas 20, 022114 (2013)]. For the weak shear flows below an amplitude threshold, v{sub c}, at which two DTM eigen states with antisymmetric or symmetric magnetic island structure are degenerated, the zonal flows grow oscillatorily in the Rutherford regime during the nonlinear evolution of the DTMs. It is identified that the oscillation mechanism results from the nonlinear interaction between the distorted islands and the zonal flows through the modification of shear flows. However, for the medium shear flows above v{sub c} but below the critical threshold of the KelvinHelmholtz instability, an oscillatory growing zonal flow occurs in the linear phase of the DTM evolution. It is demonstrated that the zonal flow oscillation originates from the threewave mode coupling or a modulation instability pumped by two DTM eigen modes with the same frequency but opposite propagating direction. With the shear flows increasing, the amplitude ofmore »
 Authors:
 School of Physics and Optoelectronic Technology, Dalian University of Technology, Dalian 116024 (China)
 (Japan)
 Graduate School of Energy Science, Kyoto University, Uji, Kyoto 6110011 (Japan)
 Publication Date:
 OSTI Identifier:
 22252889
 Resource Type:
 Journal Article
 Resource Relation:
 Journal Name: Physics of Plasmas; Journal Volume: 21; Journal Issue: 5; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
 Country of Publication:
 United States
 Language:
 English
 Subject:
 70 PLASMA PHYSICS AND FUSION TECHNOLOGY; 71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; DOPPLER EFFECT; EVOLUTION; HELMHOLTZ INSTABILITY; MAGNETIC ISLANDS; MAGNETOHYDRODYNAMICS; NONLINEAR PROBLEMS; OSCILLATIONS; SHEAR; SIMULATION; SYMMETRY; TEARING INSTABILITY
Citation Formats
Mao, Aohua, Graduate School of Energy Science, Kyoto University, Uji, Kyoto 6110011, Li, Jiquan, Email: lijq@energy.kyotou.ac.jp, Liu, Jinyuan, Email: jyliu@dlut.edu.cn, Kishimoto, Yasuaki, and Institude of Advanced Energy, Kyoto University, Uji, Kyoto 6110011. Zonal flow dynamics in the double tearing mode with antisymmetric shear flows. United States: N. p., 2014.
Web. doi:10.1063/1.4875729.
Mao, Aohua, Graduate School of Energy Science, Kyoto University, Uji, Kyoto 6110011, Li, Jiquan, Email: lijq@energy.kyotou.ac.jp, Liu, Jinyuan, Email: jyliu@dlut.edu.cn, Kishimoto, Yasuaki, & Institude of Advanced Energy, Kyoto University, Uji, Kyoto 6110011. Zonal flow dynamics in the double tearing mode with antisymmetric shear flows. United States. doi:10.1063/1.4875729.
Mao, Aohua, Graduate School of Energy Science, Kyoto University, Uji, Kyoto 6110011, Li, Jiquan, Email: lijq@energy.kyotou.ac.jp, Liu, Jinyuan, Email: jyliu@dlut.edu.cn, Kishimoto, Yasuaki, and Institude of Advanced Energy, Kyoto University, Uji, Kyoto 6110011. 2014.
"Zonal flow dynamics in the double tearing mode with antisymmetric shear flows". United States.
doi:10.1063/1.4875729.
@article{osti_22252889,
title = {Zonal flow dynamics in the double tearing mode with antisymmetric shear flows},
author = {Mao, Aohua and Graduate School of Energy Science, Kyoto University, Uji, Kyoto 6110011 and Li, Jiquan, Email: lijq@energy.kyotou.ac.jp and Liu, Jinyuan, Email: jyliu@dlut.edu.cn and Kishimoto, Yasuaki and Institude of Advanced Energy, Kyoto University, Uji, Kyoto 6110011},
abstractNote = {The generation dynamics and the structural characteristics of zonal flows are investigated in the double tearing mode (DTM) with antisymmetric shear flows. Two kinds of zonal flow oscillations are revealed based on reduced resistive magnetohydrodynamics simulations, which depend on the shear flow amplitudes corresponding to different DTM eigen mode states, elaborated by Mao et al. [Phys. Plasmas 20, 022114 (2013)]. For the weak shear flows below an amplitude threshold, v{sub c}, at which two DTM eigen states with antisymmetric or symmetric magnetic island structure are degenerated, the zonal flows grow oscillatorily in the Rutherford regime during the nonlinear evolution of the DTMs. It is identified that the oscillation mechanism results from the nonlinear interaction between the distorted islands and the zonal flows through the modification of shear flows. However, for the medium shear flows above v{sub c} but below the critical threshold of the KelvinHelmholtz instability, an oscillatory growing zonal flow occurs in the linear phase of the DTM evolution. It is demonstrated that the zonal flow oscillation originates from the threewave mode coupling or a modulation instability pumped by two DTM eigen modes with the same frequency but opposite propagating direction. With the shear flows increasing, the amplitude of zonal flow oscillation increases first and then decreases, whilst the oscillation frequency as twice of the Doppler frequency shift increases. Furthermore, impacts of the oscillatory zonal flows on the nonlinear evolution of DTM islands and the global reconnection are also discussed briefly.},
doi = {10.1063/1.4875729},
journal = {Physics of Plasmas},
number = 5,
volume = 21,
place = {United States},
year = 2014,
month = 5
}

The effect of zonal flow shear on the double tearing mode is investigated by solving the linear reduced twofluid equations for the equilibrium including zonal flow. The zonal flow caused by microturbulence is obtained from nonlinear simulation results presented by A. Ishizawa and N. Nakajima [Phys. Plasmas 14, 040702 (2007)]. There is no clear evidence that could indicate whether the double tearing mode is stabilized or destabilized by the zonal flow.

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