GEM Postdoc: Nonlinear Scattering of Radiation-Belt Electrons by Chorus Waves

合唱是一种高度非线性的哨声模式电磁发射，在地磁活动条件下在等离子体顶外的低密度区域被激发。这种重要的磁层波可以与外辐射带电子相互作用，造成俯仰角散射损失和能量扩散。以前的波粒散射效应的计算通常是使用准线性方法进行的。本项目将量化非线性离散合唱元素对散射的影响，并将结果与拟线性理论进行比较。该方法将在模拟波场中对大量电子进行测试粒子计算，其中将构建包括合唱在高纬度传播过程中朗道阻尼的影响。这些结果随后将用于构建由合唱散射引起的降水通量的全球分布以及与之相关的电离层电导率变化。该研究与地球空间环境模拟（GEM）磁层-电离层耦合运动和美国国家航空航天局（NASA）未来辐射带风暴探测器（RBSP）任务有关。这也是2002年NRC（美国国家研究委员会）十年报告中列出的挑战“理解在太阳和空间等离子体中观察到的过程中表现出来的基本物理原理”的核心。

Chorus is a highly non-linear whistler mode electromagnetic emission, which is excited in the low-density region exterior to the plasmapause under geo-magnetically active conditions. This important magnetospheric wave can interact with outer radiation belt electrons, causing pitch-angle scattering loss and energy diffusion. Previous calculations of the effect of wave-particle scattering has generally been performed using a quasi-linear approach. This project will quantify the effects of scattering by non-linear discrete chorus elements and compare the results with quasi-linear theory. The approach will be to carry out test particle calculations for a large number of electrons in a simulated wave field, which will be constructed including the effect of Landau damping of chorus during propagation to higher latitude. The results will subsequently be used to construct the global distribution of precipitation flux due to chorus scattering and the associated changes in ionospheric conductivity. The research is relevant to the Geospace Environment Modeling (GEM) Magnetosphere-Ionosphere coupling campaign and to the future Radiation Belt Storm Probes (RBSP) mission of National Aeronautics and Space Administration (NASA). It is also central to the Challenge "Understanding the basic physical principles manifest in processes observed in solar and space plasmas" listed in the 2002 NRC (National Research Council) Decadal Report.