Electron Acceleration By Large-Amplitude Oblique Whistler Waves

磁层物理学中的一个突出问题涉及了解地球辐射带电子的来源和损耗机制。人们认为各种等离子体波在这方面起着至关重要的作用。最近的一项观测表明，可能存在相对于周围磁场斜传播的大振幅哨声波。这些波可能在加速辐射带电子在几秒钟的时间尺度内达到相对论能量方面发挥重要作用。本项目将通过求解完全非线性冷电子流体方程，结合相对论性测试粒子模拟代码，对非均匀磁场和等离子体密度下的大振幅哨声波传播进行严格研究。在这一领域，以往的研究仅限于拟线性状态、均匀的磁场和密度以及哨声波的平行传播。正在开发各种各样的基于物理的模型来预测辐射带的变化，以供空间天气应用。知道斜传播波是否是粒子加速的一个重要来源是很重要的。同样重要的是要知道在何种程度上需要对问题进行完全非线性的处理。除了与空间天气预报相关的社会效益外，该项目还具有教育效益，因为一名博士后研究员将参与这项研究。

An outstanding problem in magnetospheric physics involves understanding the source and loss mechanisms of the Earth's radiation belt electrons. It is thought that various plasma waves play an essential role in this regard. A recent observation suggests that there may be large-amplitude whistler waves propagating obliquely with respect to the ambient magnetic field. These waves may play a significant role in accelerating the radiation belt electrons to relativistic energies within a few seconds time scale. This project will rigorously study the propagation of large-amplitude whistler waves in an inhomogeneous magnetic field and plasma density by solving the fully nonlinear cold electron fluid equation coupled with relativistic test particle simulation code. Previous work in this area has been limited to the quasi-linear regime, uniform magnetic field and density and parallel propagation of the whistler waves. A wide variety of physics based models are being developed to forecast radaition belt variations for space weather applications. It is important to know whether or not obliquely propagating waves are an important source of particle acceleration. It is similary important to know to what extent a fully nonlinear treatment of the problem is required. In addition to the societal benefits of this research because of its relevance to space weather forecasting, the project has educational benefits as well because a postdoctoral researcher will participate in the research.