Nonlinear Plasma Waves at the Earth's Bow Shock

地球弓激波中的非线性等离子体波

• 批准号: 9021985
• 负责人: Steven Spangler
• 金额: $ 15.5万
• 依托单位: University of Iowa
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1991
• 资助国家: 美国
• 起止时间: 1991-04-01 至 1993-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9021985&HistoricalAwards=false
• 关键词: Nonlinear; Plasma; Waves; Earth; Bow

It is intended to carry out several theoretical and observational studies related to nonlinear MHD waves and Langmuir waves in the region of space upstream to the Earth's bowshock. It is planned to compare the large amplitude MHD waves, and in particular their steepened appearance, to the solutions of nonlinear wave equations such as the Derivative Nonlinear Schrondinger Equation (DNLS). Efforts will be made to append terms to the DNLS which describe important physical effects such as resonant particle interactions, realistic particle distribution functions, oblique propagation, and two and three dimensionality. An extensive investigation, currently in progress, of the various linear and nonlinear wave processes which are important in the upstream MHD waves will be completed. Twenty periods of upstream wave activity have been identified, the data acquired, and power spectra and cross correlation functions calculated. New work will address the extent to which pondermotive nonlinearities, the parametric decay instability, and three dimensional wave effects can be discerned in the data. In the study of Langmuir waves, work will concentrate on further numerical and analytic studies of the saturated phase of the beam instability using computer simulations in part. The goal of these studies will be to better understand such phenomena as wave backscattering, generation of low frequency waves, and the long time evolution of the beam-driven waves.

它旨在进行几个理论和 与非线性磁流体力学波和朗缪尔有关的观测研究 在地球弓形激波上游的空间区域中的波。 计划比较大振幅MHD波， 特别是它们陡峭的外观，以解决 非线性波动方程，如导数非线性 薛定谔方程（DNLS）。 将努力增加 DNLS中描述重要物理效应的术语， 作为共振粒子相互作用，现实粒子 分布函数，斜传播，以及二和三 维度 一项广泛的调查，目前在 各种线性和非线性波过程的进展 这是重要的上游磁流体波将完成。 已经确定了20个上游波浪活动周期， 所获得的数据、功率谱和互相关 功能计算 新的工作将解决在多大程度上， 有质动力非线性，参量衰减不稳定性， 并且可以在数据中辨别三维波浪效应。 在朗缪尔波的研究中，工作将集中在进一步的 梁的饱和相的数值分析 不稳定性的计算机模拟。 的目标 这些研究将有助于更好地理解波 反向散射，低频波的产生，以及长 束驱动波的时间演化。