Simulations of high Mach number perpendicular shocks with resistive electrons
Simulations of high Mach number perpendicular shocks with resistive electrons
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电阻电子高马赫数垂直冲击的模拟
DOI：
10.1029/ja091ia08p08805
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发表时间：
1986
影响因子：
--
通讯作者：
K. Quest
中科院分区：
文献类型：
--
作者：
K. Quest
本文用模拟程序对高马赫数垂直激波的结构进行了研究，该程序将离子视为宏观粒子，将电子视为电阻性无质量流体。结果表明，当上游等离子体β e1的阿尔芬马赫数MA在5 ~ 60之间时，可以找到稳定的稳态激波解，其中β定义为等离子体压力与磁压力之比，前提是上游电阻扩散长度远小于离子惯性长度csωpi。如果电阻扩散长度大于0.4csωpi，则磁场超调被抑制，并且电子动量方程的不平衡导致反射离子分数的周期性波动。在极限MA≤10时，随着MA的增加，磁场超调量和反射离子的比例增加，与之前的结果一致。当马赫数较高时，反射离子的比例在约40p处达到峰值，而磁场超调的增加速度要慢得多。这些结果与由电子动量方程导出的简单标度定律一致。讨论了上游β和电子惯性效应的重要性。
The structure of high Mach number perpendicular shocks is examined using a simulation code which treats the ions as macroparticles and the electrons as a resistive massless fluid. It is shown that stable, stationary shock solutions can be found for Alfven Mach numbers MA between 5 and 60 for upstream plasma β e 1, where β is defined as the ratio of the plasma pressure to the magnetic pressure, provided that the upstream resistive diffusion length is much smaller than the ion inertial length csωpi. If the resistive diffusion length is larger than 0.4csωpi, then the magnetic field overshoot is damped, and an imbalance in the electron momentum equation results in a periodic fluctuation of the fraction of reflected ions. In the limit MA ≤ 10, the magnetic field overshoot and the fraction of reflected ions increase with increasing MA, consistent with earlier results. At higher Mach numbers the fraction of reflected ions peaks at approximately 40p and the magnetic field overshoot increases at a much slower rate. These results are consistent with simple scaling laws derived from the electron momentum equation. The importance of upstream β and electron inertial effects are discussed.