标题： 电磁电子开尔文-亥姆霍兹不稳定现象 显示英文标题

标题： Electromagnetic Electron Kelvin-Helmholtz Instability

摘要： 在电子动能尺度上，离子和电子解耦，在电子惯性长度 $\sim d_e$ 上的电子速度剪切可以触发电磁（EM）电子Kelvin-Helmholtz不稳定性（EKHI）。在本文中，我们研究了无粘性碰撞less等离子体中具有阶跃函数电子剪切流的EM EKHI的解析性质。我们表明，在不可压缩的碰撞less等离子体中，必须打破理想的电子冻结条件 $\mathbf{E} + \mathbf{v}_e \times \mathbf{B}/c = 0$ 才能发生EM EKHI。在阶跃函数电子剪切流中，理想的电子冻结条件被磁通量守恒所取代，即 $\nabla \times (\mathbf{E} + \mathbf{v}_e\times \mathbf{B}/c) = 0$，导致与标准的理想不可压缩磁流体力学KHI相似的色散关系。平行于电子流的磁场由于磁张力抑制了EM EKHI。EKHI的EM模式的阈值为 $(\mathbf{k}\cdot\Delta\mathbf{U}_e)^2>\frac{n_{e1}+n_{e2}}{n_{e1} n_{e2}}[n_{e1}(\mathbf{v}_{Ae1}\cdot\mathbf{k})^2+n_{e2}(\mathbf{v}_{Ae2}\cdot\mathbf{k})^2]$，其中 $\mathbf{v}_{Ae} =\mathbf{B}/(4\pi m_e n_e)^{1/2}$、$\Delta\mathbf{U}_e$和 $n_e$分别是电子流速剪切和密度。 EM模的增长率是电子回旋频率$\gamma_{em} \sim \Omega_{ce}$。 显示英文摘要

摘要： On electron kinetic scales, ions and electrons decouple, and electron velocity shear on electron inertial length $\sim d_e$ can trigger electromagnetic (EM) electron Kelvin-Helmholtz instability (EKHI). In this paper, we present an analytic study of EM EKHI in an inviscid collisionless plasma with a step-function electron shear flow. We show that in incompressible collisionless plasma the ideal electron frozen-in condition $\mathbf{E} + \mathbf{v}_e \times \mathbf{B}/c = 0$ must be broken for the EM EKHI to occur. In a step-function electron shear flow, the ideal electron frozen-in condition is replaced by magnetic flux conservation, i.e., $\nabla \times (\mathbf{E} + \mathbf{v}_e\times \mathbf{B}/c) = 0$, resulting in a dispersion relation similar to that of the standard ideal and incompressible magnetohydrodynamics KHI. The magnetic field parallel to the electron streaming suppresses the EM EKHI due to magnetic tension. The threshold for the EM mode of the EKHI is $(\mathbf{k}\cdot\Delta\mathbf{U}_e)^2>\frac{n_{e1}+n_{e2}}{n_{e1} n_{e2}}[n_{e1}(\mathbf{v}_{Ae1}\cdot\mathbf{k})^2+n_{e2}(\mathbf{v}_{Ae2}\cdot\mathbf{k})^2]$, where $\mathbf{v}_{Ae} =\mathbf{B}/(4\pi m_e n_e)^{1/2}$, $\Delta\mathbf{U}_e$ and $n_e$ are the electron streaming velocity shear and densities, respectively. The growth rate of the EM mode is $\gamma_{em} \sim \Omega_{ce}$, the electron gyro-frequency.