Roles of super-Alfvenic shear flows on Kelvin-Helmholtz and tearing instability in compressible plasma
Roles of super-Alfvenic shear flows on Kelvin-Helmholtz and tearing instability in compressible plasma
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DOI：
10.1088/0031-8949/86/04/045503
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发表时间：
2012-10-01
期刊：
影响因子：
2.9
通讯作者：
Ma, Z. W.
中科院分区：
文献类型：
--
作者：
Li, J. H.;Ma, Z. W.
利用二维可压缩磁流体力学方程研究了超阿尔芬剪切流下的Kelvin-Helmholtz （KH）不稳定性和撕裂模式不稳定性。剪切流平行于磁力线。研究了等离子体β和剪切流速度nu(0)的宽范围。在可压缩等离子体中，发现有两个临界速度nu（c1）和nu(c2)，它们与β相关。当nu(A) < nu(0) < nu（c1）时，KH不稳定性为纯生长模态。当nu(c1) < nu(0) < nu（c2）时，KH不稳定性随振荡增大。当nu(0) > nu（c2）时，不稳定性完全稳定。当KH不稳定性占主导地位时，在线性生长阶段之后总会有一个由撕裂模式不稳定性引发的爆炸阶段。当剪切流厚较小时，KH不稳定性占主导地位，当剪切流厚足够大时，撕裂不稳定性占主导地位。
The Kelvin-Helmholtz (KH) instability and the tearing mode instability under super-Alfvenic shear flow have been studied using two-dimensional compressible magnetohydrodynamic equations. The shear flow is parallel to the magnetic field line. A broad range of the plasma beta and of the shear flow speed nu(0) are investigated. In compressible plasma, it is found that there are two critical velocities nu(c1) and nu(c2), which are beta-related. When nu(A) < nu(0) < nu(c1), the KH instability is a pure growing mode. When nu(c1) < nu(0) < nu(c2), the KH instability grows with oscillation. The instability is fully stabilized when nu(0) > nu(c2). When the KH instability is dominant, there is always an explosive phase triggered by the tearing mode instability after the linear growing phase. For a small shear flow thickness, the KH instability is dominant, while tearing instability becomes dominant when the shear flow thickness is large enough.