Nonlinear Wave-particle Interactions

该奖项是根据2009年《美国复苏和再投资法案》(公法111-5)提供资金的。该项目由地球科学局大气科学司和数学和物理科学局物理司联合资助。该项目将通过加州大学洛杉矶分校的大型等离子体设备(LAPD)，采用理论/数值模拟和实验相结合的方法，研究相对论电子和哨声模波之间的非线性波-粒子相互作用。其动机是了解地球辐射带的动力学，这是磁层物理学中一个关键的悬而未决的问题。用来模拟波粒相互作用的两种方法是：拟线性扩散理论和试验粒子模拟。准线性理论在外辐射带被打破，在那里最近观察到了大幅度的窄带相干波。该项目将利用电子和波的幅度和相位的分布来扩展最近的测试粒子方法，以便推导出高能电子与大幅度相干哨声波相互作用的更自洽的处理方法。实验将在Lapd上进行，涉及从装置一端传播的高能电子束与从另一端发射的波的相互作用。将测量光束的俯仰角和能量的变化。实验结果将与理论/数值模拟进行比较，以改进和验证理论。该项目由一名年轻的研究科学家领导，还将有一名博士后研究员和一名研究生参与。该项目具有与空间天气有关的社会影响。

This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5). The project is being funded jointly by the Division of Atmospheric Sciences of the Geosciences Directorate and by the Division of Physics in the Mathematical and Physical Sciences Directorate.This project will study nonlinear wave-particle interactions between relativistic electrons and whistler mode waves with a combination of theory/numerical simulation and experiment via the Large Plasma Device (LAPD) at UCLA. The motivation is to understand the dynamics of Earth's radiation belts, which is a critical unresolved problem in magnetospheric physics. There is a dichotomy between the two methods used to model wave-particle interactions: namely quasilinear diffusion theory and the test-particle simulations. The quasilinear theory breaks down in the outer radiation belt where large amplitude, narrow-band coherent waves have recently been observed. The porject will extend a recent test particle approach using a distribution of electrons and wave amplitudes and phases in order to derive a more self-consistent treatment of the interaction of energetic electrons with large amplitude coherent whistler waves. Experiments will be carried out on the LAPD involving the interaction of an energetic electron beam propagating from one end of the device with waves launched from the other end. The change in the pitch-angle and energy of the beam will be measured. The experimental results will compared to the theoretical/numerical simulations to improve and validate the theory.The project is headed by a young research scientist and will also involve a postdoctoral researcher and a graduate student. The project has societal impacts related to space weather.