Ion thermal effects on E-region instabilities: linear theory
Ion thermal effects on E-region instabilities: linear theory
复制标题
离子热效应对 E 区不稳定性的影响：线性理论
DOI：
10.1016/j.jastp.2004.07.006
复制
发表时间：
2004
影响因子：
1.9
通讯作者：
M. Oppenheim
中科院分区：
文献类型：
--
作者：
Y. Dimant;M. Oppenheim
电离层电射流中的线性不稳定性和湍流过程导致形成等离子体密度不规则性，从而产生强烈的雷达反射。对这些不规则性的研究集中在Farley-Buneman（FB）和梯度漂移不稳定性的作用上，假设等离子体的行为是等温或等温的。在过去的十年中，这一限制已经放松，导致D和E区的热驱动不稳定性的预测，现在有一些支持的观测证据。甚至最近，完全动力学粒子在细胞（PIC）模拟表明，离子热效应强烈修改FB不稳定的非线性行为，特别是在顶部的电射流。本文介绍了FB和热不稳定性组合的线性理论。该理论预测，不稳定性将发展在一个更广泛的高度范围比绝热或等温FB不稳定性预测。它还预测，热修改FB波的优选方向可能会显着不同于标准的Farley-Buneman波。这些理论发展具有重要的观测结果。
Linear instabilities and turbulent processes in ionospheric electrojets lead to the formation of plasma density irregularities which create strong radar reflections. Studies of these irregularities have focused on the role of the Farley–Buneman (FB) and gradient drift instabilities with the assumption that the plasma behaves isothermally or adiabatically. In the last decade, this restriction has been relaxed, resulting in the prediction of D and E-region thermally driven instabilities, which now have some supporting observational evidence. Even more recently, fully kinetic particle-in-cell (PIC) simulations show that ion thermal effects strongly modify the nonlinear behavior of the FB instability, especially at the top of the electrojet. This paper describes the linear theory of the combined FB and thermal instabilities. The theory predicts that instabilities will develop over a wider range of altitudes than predicted for the adiabatic or isothermal FB instability. It also predicts that preferred directions of thermally modified FB waves may differ significantly from that of standard Farley–Buneman waves. These theoretical developments have important observational consequences.