Nakamura T K M, Hayashi D, Fujimoto M, Shinohara I
Department of Earth and Planetary Sciences, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro, Tokyo 152-8551, Japan.
Phys Rev Lett. 2004 Apr 9;92(14):145001. doi: 10.1103/PhysRevLett.92.145001.
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.
我们通过包含有限电子惯性效应的二维双流体系统模拟了磁流体动力学（MHD）尺度的开尔文-亥姆霍兹（KH）涡旋的非线性发展。在剪切层存在适度密度跃变的情况下，与磁流体动力学结果形成鲜明对比的是，发现磁流体动力学KH涡旋在一个涡旋周转完成时就会衰减。这种衰减是由出现在母涡旋内的较小涡旋介导的，即使剪切层宽度增大，这种衰减仍然有效。结果表明，较小的涡旋基本上具有磁流体动力学性质，而这些涡旋的产生是由电子惯性效应实现的。文中还讨论了这些结果在磁尾边界层中的应用。
