Bernstein instability driven by thermal ring distribution
Bernstein instability driven by thermal ring distribution
复制标题
热环分布驱动的伯恩斯坦不稳定性
DOI：
10.1063/1.4887000
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发表时间：
2014
影响因子：
2.2
通讯作者：
A. Qamar
中科院分区：
文献类型：
--
作者：
P. Yoon;F. Hadi;A. Qamar
经典的伯恩斯坦波可能与实验室等离子体、地球和其他行星磁层中检测到的带状发射密切相关。然而，伯恩斯坦波的惯常讨论是基于各向同性的热速度分布函数。为了理解如何激发这种波，我们需要一种发射机制，即不稳定性。在非相对论性无碰撞等离子体中，唯一已知的伯恩斯坦波不稳定性与冷垂直速度环分布函数相关。然而，冷环分布是高度理想化的。本简报将冷环分布模型推广到包括热扩散，以便通过更现实的电子分布函数来描述伯恩斯坦环不稳定性，从而证明了与环分布相关的热扩散的稳定性。目前的发现意味着伯恩斯坦波的激发需要与电子分布函数相关的足够高的垂直速度梯度。
The classic Bernstein waves may be intimately related to banded emissions detected in laboratory plasmas, terrestrial, and other planetary magnetospheres. However, the customary discussion of the Bernstein wave is based upon isotropic thermal velocity distribution function. In order to understand how such waves can be excited, one needs an emission mechanism, i.e., an instability. In non-relativistic collision-less plasmas, the only known Bernstein wave instability is that associated with a cold perpendicular velocity ring distribution function. However, cold ring distribution is highly idealized. The present Brief Communication generalizes the cold ring distribution model to include thermal spread, so that the Bernstein-ring instability is described by a more realistic electron distribution function, with which the stabilization by thermal spread associated with the ring distribution is demonstrated. The present findings imply that the excitation of Bernstein waves requires a sufficiently high perpendicular velocity gradient associated with the electron distribution function.