在静电离子迴旋波中电子分布的演化及不稳定性分析

静电离子迴旋波可以导致异常电阻及平行电场的出现.本文分析了电子分布函数在这种波场及平行电场中的演化.结果表明, 电子分布可分成捕获和逃逸两部分.双流不稳定性的发展使逃逸部分变平, 形成具有长而平的尾巴的分布函数.后者在一定速度空间范围内对异常迴旋共振是不稳定的, 结果导致电子的热化和投掷角扩散, 使电子损失掉平行方向的能量, 形成尾部隆起的分布特征, 导致新的不稳定性的出现, 使隆起的部分基本拉平.此后虽然有少部分电子仍可能被加速, 但要慢得多, 且边加速边被热化. 

Evolution of Electron Distributions in Electrostatic ionCyclotron Waves With Associated Parallel ElectricField and Analysis of Resulting Instabilities

Electrostatic ion cyclotron wave (EIC)can induce anormalous resistivity and parallel electric field. In this paper, evolution of distributions of electrons is analyzed.The results show that the distribution can be divided in two groups-trapped part andrun-away part. Two-stream instability can flatten the distribution of the run-away electrons, resulting in a distribution with a long and flat tail. Such kind of distribution is instable to anormalous cyclotron resonance is certain velocity space, resulting in thermalization and pitch-angle scattering of the electrons, therefore the losses of parallel velocity of the electrons. As a result of development of such instability, a bump-on-tail distribution can be established, and a new instability develops and results in flattenning of the bump-on-tail. This instability can ramp the parallel velocity around a critical value. After that, although small part of electrons can be accelerated further, but very slowly, at same time be thermalized.Finally, the results of this paper are compared with the observation results of the wave fields and precipitating electrons, and general consistency is showed.