电子声波的激发及其对极光粒子加速的影响研究

电离层顶部源自电离层的冷电子密度与来自磁层的热电子密度接近，形成过渡区。最近的研究表明，当动力Alfven波传播到过渡区时，电子声波被激发，并可以加速电子。以往对于电子声波的激发机制及其对粒子加速的贡献并没有得到很多关注。本项目拟在已有的自洽模型基础上模拟电子声波的激发，计算波的反射系数、透射系数和波模耦合系数，以此研究电子声波的激发及其对背景参数的依赖性。另外，利用模型计算电子声波对电子加速的效率，分析其对粒子加速的贡献。本项目拟将一维模型拓展至二维，在二维条件下分析电子声波的激发及动力Alfven波的波谱展宽、相位混合等效应对电子声波加速电子的影响。

In the topside ionosphere, the density of cold electrons from the ionosphere becomes comparable to the density of hot electrons from the magnetosphere. It was shown that when the kinetic waves propagate into the transition region, the steep temperature gradient leads to the generation of the electron acoustic wave. The generation of electron acoustic mode and the electron acceleration by electron acoustic wave has received little attention because their propagation speed is close to the electron thermal speed and therefore these waves decay rapidly. Based on a drift-kinetic model, the reflection coefficient, transmission coefficient of the kinetic Alfven waves and the mode conversion from kinetic Alfven wave to electron acoustic wave will be calculated to study the generation of electron acoustic wave and its dependence on the background parameters. The contribution of the electron acoustic wave on the electron acceleration will be investigated. The model will be developed to two dimension to study the generation of the electron acoustic wave and the effect of wave broadening and the phase mixing on the electron acceleration by electron acoustic wave.