Numerical Studies of Magnetospheric Dynamics and Related Space Plasma Processes

磁层动力学及相关空间等离子体过程的数值研究

• 批准号: 9201662
• 负责人: John Dawson
• 金额: $ 53.97万
• 依托单位: University of California-Los Angeles
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1992
• 资助国家: 美国
• 起止时间: 1992-08-01 至 1996-01-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9201662&HistoricalAwards=false
• 关键词: Numerical; Studies; Magnetospheric; Dynamics; Related

This proposal is for numerical studies of the magnetosphere with a focus on the properties of intermediate shock waves, the dynamics of the magnetosheath and magnetopause, reconnection and convection in the geomagnetic tail, and auroral electron acceleration by lower-hybrid wave turbulence. Scaling behavior of intermediate shocks will be handled through magnetohydrodynamics (MHD) followed by hybrid simulations extended to the high ion beta case (beta is the ratio of plasma to field energy density). MHD studies of the magnetopause will be pursued along with hybrid models to study magnetopause structure. 3D global simulations will be done including all the large-scale dynamics of the magnetosphere to test the effects of magnetosheath and magnetopause boundary conditions. Response of the magnetosphere to these inputs will be analyzed through studies of collisionless reconnection in the near- Earth plasma sheet, extended to cover more general aspects of convection and to consider the structure and stability of more distant parts of the tail current sheet. A new high beta drift- kinetic simulation code will be developed including some kinetic effects for the electrons as well as ions. This code will be used to test the hypothesis that chaotization of electron orbits can restore the universal ion tearing mode - a fundamental question for the reconnection process in space plasmas. Resonant electron acceleration by ion wave turbulence will be studied and the results compared with observations of auroral electron spectra and the structure of auroral arcs.

这项建议用于磁层的数值研究，重点是中间激波的性质、磁鞘和磁层顶的动力学、地磁尾部的重联和对流以及低杂波湍流对极光电子的加速。中间激波的标度行为将通过磁流体动力学(MHD)处理，然后扩展到高离子β(β是等离子体与场能量密度的比率)的混合模拟。磁层顶的磁流体研究将与研究磁层顶结构的混合模型一起进行。将进行包括所有大尺度磁层动力学的3D全球模拟，以测试磁鞘和磁层顶边界条件的影响。将通过研究近地等离子体片中的无碰撞重联来分析磁层对这些输入的响应，该研究扩展到涵盖对流的更一般方面，并考虑尾电流片更远部分的结构和稳定性。将开发一个新的高贝塔漂移动力学模拟程序，包括电子和离子的一些动力学效应。这个代码将被用来检验这样一个假设，即电子轨道的混沌可以恢复普遍的离子撕裂模式--这是空间等离子体中重联过程的一个基本问题。我们将研究离子波湍流对电子的共振加速作用，并将其结果与极光电子光谱和极光弧结构的观测结果进行比较。