Multipoint Observations of Compressional Pulsations: Testing Possible Generation Mechanisms

压缩脉动的多点观测：测试可能的产生机制

• 批准号: 1207445
• 负责人: Galina Korotova
• 金额: $ 30万
• 依托单位: University of Maryland, College Park
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-09-01 至 2019-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1207445&HistoricalAwards=false
• 关键词: Multipoint; Observations; Compressional; Pulsations; Testing

The ultra-low frequency (3 to 15 minute periods) electromagnetic waves called Pc 5 pulsations have been studied for over 50 years. They are an important magnetospheric phenomenon because they convert energy from one form to another and transmit energy from one location to another. Although there have been a number of physical explanations proposed for these waves their origin remains unknown. This proposal seeks to determine the origin of one class of these waves ? compressional Pc 5 pulsations. The Principal Investigator of this proposal will be assisted by a graduate student in carrying out this research protocol. These are waves in the Pc 5 frequency range for which there are oscillations along the direction of the background magnetic field. Three mechanisms have been proposed for these waves: drift mirror instabilities due to pressure anisotropies, drift bounce instabilities and injection of blobs of plasma sheet plasma into the inner magnetosphere. The combination of THEMIS observations near the equator and Cluster observations in polar orbit now makes it possible to determine which of these mechanisms are operating. The following questions have been identified for study: 1. What mechanism generates compressional pulsations in the dawn and dusk magnetosphere? 2. What are the characteristics of the compressional pulsations, including their spatial extent and latitudinal structure? 3. What mechanism generates the subcategory of compressional waves exhibiting frequency doubling (the frequency of the compression component of the waves is twice that of the transverse components) and how do suprathermal particles respond to the pulsations?

被称为 Pc 5 脉动的超低频（3 至 15 分钟周期）电磁波的研究已超过 50 年。它们是一种重要的磁层现象，因为它们将能量从一种形式转换为另一种形式，并将能量从一个位置传输到另一个位置。 尽管已经对这些波提出了许多物理解释，但它们的起源仍然未知。该提案旨在确定其中一类波浪的起源？压缩性 Pc 5 脉动。本提案的首席研究员将由一名研究生协助执行本研究方案。 这些是 Pc 5 频率范围内的波，沿着背景磁场的方向存在振荡。对于这些波，人们提出了三种机制：由于压力各向异性导致的漂移镜不稳定性、漂移反弹不稳定性以及等离子体片状等离子体斑点注入内磁层。 赤道附近的 THEMIS 观测和极轨道的 Cluster 观测相结合，现在可以确定哪些机制正在运行。 已确定以下问题供研究： 1. 黎明和黄昏磁层中产生压缩脉动的机制是什么？ 2. 压缩脉动的特征是什么，包括其空间范围和纬向结构？ 3. 什么机制产生表现出倍频的压缩波子类（波的压缩分量的频率是横向分量的频率）以及超热粒子如何响应脉动？