Analysis of Plasma Wave Growth, Anomalous Resistivity, and Diffusion in the Dayside Magnetopause and Reconnection Region

日侧磁层顶和重联区等离子波生长、反常电阻率和扩散的分析

• 批准号: 0443531
• 负责人: J. Douglas Menietti
• 金额: $ 21万
• 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: 2005
• 资助国家: 美国
• 起止时间: 2005-02-01 至 2009-01-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0443531&HistoricalAwards=false
• 关键词: Analysis; Plasma; Wave; Growth; Anomalous

The effectiveness of plasma waves in providing sufficient anomalous resistivity in the reconnection region of the dayside magnetospause is an important and as-yet unresolved question. Plasma wave observations of the magnetopause/magnetosheath by the plasma wave instrument on board the Polar spacecraft have shown the correspondence between different wave modes and probable reconnection sites. The plasma wave instrument (PWI) on board Polar has the unique capability of positively identifying waves using 3 axis electric and magnetic observations at unprecedented resolutions. A one-dimensional electrostatic Vlasov simulation code has been used to investigate the role of ion acoustic waves in providing the necessary anomalous resistivity along the magnetopause reconnection region. The results have shown that analytical estimates of weak quasilinear effects were incorrect. These studies make a strong case for further non-linear studies of diffusion coefficients in the magnetopause region. This project will use the unique capabilities of the PWI on board the Polar spacecraft along with newly developed analysis tools to more accurately classify and analyze waves in this region. Observed plasma distribution functions which include electron and ion beams will be modeled to determine the existence and growth rates of the observed waves. Linear calculations will provide a benchmark for subsequent non-linear Vlasov and particle-in-cell (hybrid) simulations. The PWI high resolution waveform data will be used to determine wave modes and propagation properties. A newly developed compressible MHD mode analysis will be used to distinguish fast and slow mode waves at low frequencies. Particular attention will be given to the role of waves in providing anomalous/diffusive resistivity along the magnetopause and in the reconnection region. Particle-in-cell (PIC) and hybrid codes will be used to study the non-linear diffusion of waves along the magnetopause, including lower hybrid (LH), whistler mode and low-frequency electromagnetic modes. The results will complement the previous non-linear studies of the reconnection region. This work will involve the significant efforts of an undergraduate research assistant in the space physics program at the University of Iowa, as well as three visiting scholars from the Czech Republic.

等离子体波在日侧磁层序重联区提供足够的异常电阻率的有效性是一个重要而尚未解决的问题。极地航天器上的等离子体波仪器对磁层顶/磁鞘的等离子体波观测表明，不同的波模式和可能的重联地点之间存在对应关系。极星上的等离子体波仪器(PWI)具有利用三轴电磁观测以前所未有的分辨率积极识别波的独特能力。一维静电Vlasov模拟程序被用来研究离子声波在沿磁层顶重联区域提供必要的反常电阻率方面的作用。结果表明，对弱拟线性效应的分析估计是不正确的。这些研究为进一步对磁层顶区的扩散系数进行非线性研究提供了有力的证据。该项目将使用极地航天器上的PWI的独特能力以及新开发的分析工具来更准确地分类和分析这一区域的波。观测到的等离子体分布函数，包括电子束和离子束，将被模拟以确定观测到的波的存在和增长率。线性计算将为后续的非线性Vlasov和单元中粒子(混合)模拟提供基准。PWI高分辨率波形数据将用于确定波模式和传播特性。一种新开发的可压缩MHD模式分析将用于区分低频的快模式和慢模式波。将特别注意波在沿磁层顶和重联区提供异常/扩散电阻率方面的作用。粒子单元(PIC)和混合程序将被用来研究波沿磁层顶的非线性扩散，包括低混杂波(L H)、哨声模和低频电磁模。这一结果将补充以前对重联区的非线性研究。这项工作将涉及爱荷华大学空间物理方案的一名本科生研究助理以及来自捷克共和国的三名访问学者的重大努力。