Collaborative Research: Non-linear Physics of the Interaction Between a Relativistic Electron Beam and Magnetized Plasma: An Integrated Experimental and Modeling Approach

该项目采用实验室实验和计算机模拟相结合的方法，研究以接近光速运动的电子束如何与空间等离子体相互作用。这是一个既基本又实际的问题，与空间物理学和天体物理学中的许多具有挑战性的问题有关。例如，众所周知，空间中的高能粒子对通信卫星构成危险；有人提出，这种高能粒子可以通过未来航天器上直接产生的电子束产生的波从近地空间中移除。这项工作将详细研究电子束可以产生的波的类型以及这些波如何在空间等离子体中传播。除了为未来的空间实验提供科学基础外，这一合作项目还将为明尼苏达大学的本科生和研究生提供实验室等离子体技术培训。该项目旨在为理解和预测相对论（能量在0.1-1 MeV范围内）、有限尺寸、调制光束和磁化等离子体之间的耦合提供一个实验验证的理论框架。大多数早期的研究都集中在低能量束上，当航天器在低密度磁层等离子体中运行时，由于航天器的充电效应，这些光束不能向周围的等离子体提供显著的能量。相对而言，人们对用MeV光束激发感兴趣的等离子体波（例如whistler）的可能性知之甚少。该项目将结合理论、二维和三维动力学模拟，并在位于加州大学洛杉矶分校的基础等离子体科学设施的大型等离子体设备上进行实验室实验，该设施是由美国国家科学基金会和美国能源部共同支持的用户设施。这些实验将利用洛斯阿拉莫斯国家实验室最近开发的一种独特的可变能量电子束源，该电子束源将允许进行前所未有的电子束参数扫描。

This project uses a combination of laboratory experiments and computer simulations to study how electron beams moving with speeds approaching the speed of light interact with space plasmas. This is both a fundamental and practical problem that is relevant to many challenging issues in space physics and astrophysics. For example, it is well known that energetic particles in space pose a danger to communication satellites; and it has been proposed that such energetic particles could be removed from near-Earth regions of space by waves generated via electron beams produced directly on future spacecraft. This work will investigate in detail the types of waves that can be produced by electron beams and how such beams propagate through space plasmas. In addition to providing the scientific basis for future space-borne experiments, this collaborative project will also provide training in laboratory plasma techniques for undergraduate and graduate students at the University of Minnesota.The project aims to provide an experimentally validated theoretical framework for understanding and predicting the coupling between a relativistic (with energies in the range of 0.1-1 MeV), finite size, modulated beam and magnetized plasmas. Most earlier investigations have focused on low energy beams that cannot deliver significant power to the surrounding plasma when emitted from a spacecraft operating in a low-density magnetospheric plasma due to spacecraft charging effects. Comparatively little is known about possibility of exciting plasma waves of interest (e.g. whistler) with MeV beams. The project will combine theory, two-dimensional, and three-dimensional kinetic simulations, and laboratory experiments performed on the Large Plasma Device at the Basic Plasma Science Facility, a user facility located at UCLA and jointly supported by NSF and DOE. These experiments will utilize a unique variable-energy electron beam source recently developed at the Los Alamos National Laboratory that will allow for an unprecedented electron beam parameter scan.