Decay of MHD-scale Kelvin-Helmholtz vortices mediated by parasitic electron dynamics
Decay of MHD-scale Kelvin-Helmholtz vortices mediated by parasitic electron dynamics
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DOI：
10.1103/physrevlett.92.145001
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发表时间：
2004-04-09
影响因子：
8.6
通讯作者：
Shinohara, I
中科院分区：
文献类型：
--
作者：
Nakamura, TKM;Hayashi, D;Shinohara, I
我们用包含有限电子惯性效应的二维双流体系统模拟了MHD尺度开尔文-亥姆霍兹(KH)涡旋的非线性发展。在切变层上存在中等密度跳跃的情况下，与MHD结果形成鲜明对比的是，MHD KH涡旋在一个涡旋周转完成时就会减弱。衰减是由出现在母涡中的较小的涡来调节的，即使在剪切层宽度变大的情况下也保持有效。结果表明，较小的涡旋基本上是MHD性质的，而对这些较小涡旋的播种是通过电子惯性效应实现的。讨论了结果在磁尾边界层中的应用。
We have simulated nonlinear development of MHD-scale Kelvin-Helmholtz (KH) vortices by a two-dimensional two-fluid system including finite electron inertial effects. In the presence of moderate density jump across a shear layer, in striking contrast to MHD results, MHD KH vortices are found to decay by the time one eddy turnover is completed. The decay is mediated by smaller vortices that appear within the parent vortex and stays effective even when the shear layer width is made larger. It is shown that the smaller vortices are basically of MHD nature while the seeding for these is achieved by the electron inertial effect. Application of the results to the magnetotail boundary layer is discussed.