Collisionless Mechanisms for Energy and Momentum Exchange in Space Plasma

空间等离子体能量和动量交换的无碰撞机制

基本信息

批准号：
9123650
负责人：
D. Asoka Mendis
金额：
$ 16.35万
依托单位：
University of California-San Diego
依托单位国家：
美国
项目类别：
Continuing Grant
财政年份：
1992
资助国家：
美国
起止时间：
1992-07-01 至 1994-09-30
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=9123650&HistoricalAwards=false
关键词：
Collisionless Mechanisms Energy Momentum Exchange

项目摘要

It is a goal of our proposals to investigate the collisionless processes for energy and momentum exchange in plasma via excitation and absorption of plasma waves. Two different types of waves are to be considered: Alfven waves that organize the momentum transfer between counterstreaming ion populations via pitch angle scattering of resonant particles and lower hybrid waves that are very effective in energy transfer from ion sources of free energy to plasma electrons. For Alfven waves we are planning the solution of two following problems: the excitation of strongly nonlinear Alfven waves in a form of shocklets by counterstreaming ions, appearing in the solar wind in the upstream region of planetary and cometary bow-shocks, and the cosmic ray transport by galactic wind due to coupling between these two plasmas caused by Alfven waves. For lower hybrid waves, excited by ion beams in a plasma, the nonlinear theory is to be contructed describing the saturation of the lower hybrid instability by nonlinear wave cascading and wave absorption by plasma electrons and ions. The most important cascade mechanism that is to be under detailed analysis, is the modulational instability and collaspe of lower hybrid waves. Finally, as the possible example of collective interactions in collisional dominated plasma, the formation of the weak electrostatic shock inside the cometary ionosphere would be considered.

我们建议的目标是通过等离子体波的激发和吸收来研究等离子体中能量和动量交换的无碰撞过程。需要考虑两种不同类型的波：阿尔文波，通过共振粒子的俯仰角散射组织逆流离子群之间的动量传递；以及较低的混合波，在从自由能离子源到等离子体电子的能量传递中非常有效。对于阿尔文波，我们计划解决以下两个问题：逆流离子以激波形式激发强非线性阿尔文波，出现在行星和彗星弓形激波上游区域的太阳风中，以及宇宙射线由于阿尔文波引起的这两个等离子体之间的耦合，银河风进行了传输。对于由等离子体中的离子束激发的低混合波，将构建非线性理论来描述通过非线性波级联以及等离子体电子和离子的波吸收来描述低混合不稳定性的饱和。需要详细分析的最重要的级联机制是低层混合波的调制不稳定性和塌陷。最后，作为碰撞主导等离子体中集体相互作用的可能例子，将考虑彗星电离层内部弱静电激波的形成。