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Study on nonlinear wave dynamics in the magnetosphere via computer experiments and plasma waveform analysis

通过计算机实验和等离子体波形分析研究磁层中的非线性波动力学

基本信息

批准号：
08404027
负责人：
MATSUMOTO Hiroshi
金额：
$ 24.38万
依托单位：
KYOTO UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (A)
财政年份：
1996
资助国家：
日本
起止时间：
1996 至 1999
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-08404027/
关键词：
magnetosphere plasma waves computer experiments Waveform analysis nonlinear wave-particle interaction GEOTAIL spacecraft Electrostatic solitary wave BEN バウショックラングミュア波 GEOTAIL PWI 非線形波動波形受信器 ESW BEN

项目摘要

We have studied the nonlinear wave dynamics observed in the Earth's magnetosphere by using plasma waveform data obtained with the GEOTAIL spacecraft and by performing computer experiments with particle model. The analysis of waveforms enables us to extract the spatial as well as temporal nonlinear variation involved in each phenomenon. In particular, waveform analysis of electron modes observed at boundary layers such as the magnetic reconnection region is important in association of plasma heating, acceleration, and perturbation. The aim of this research project is to solve these microscopic nonlinear wave dynamics by performing computer experiments as well as analyzing the waveform data of GEOTAIL. We also utilized unique method in the statistical study of waveforms such as the pattern recognition as well as the conventional Fourier transformation. We paid our attention to the waveforms of broadband electrostatic noise (BEN), narrow band electrostatic noise (NEN), electron cyclotron … More harmonic waves (ECH), and amplitude modulated Langmuir waves. By combining the analysis of these waveform and computer experiments, we examined microscopic nonlinear processes in the wave dynamics.In particular, the discovery of the generation mechanism of BEN is very significant in the present research project. We, for the first time, found that BEN is made of electrostatic solitary waves (ESW) which are created by the beam-plasma interaction. By Performing computer experiments, we also revealed that ESW is a nonlinear solution of BGK mode generated by the beam-plasma instability. To statistically analyze ESW, we developed a new method using the bit-patter matching, and succeeded in extracting ESW waveforms automatically. We could clarify the relation between the propagation of ESW and that of electron beams, and the width of ESW and the local Debye length. The statistical analysis shows a good agreement with the results obtained in the computer experiments conducted in the present studies. Less

我们利用GEOTAIL航天器获得的等离子体波形数据，通过粒子模型的计算机实验，研究了在地球磁层中观测到的非线性波动动力学。对波形的分析使我们能够提取每个现象所涉及的空间和时间的非线性变化。特别是，在边界层(如磁重联区域)观察到的电子模式的波形分析对于与等离子体加热、加速和微扰有关是很重要的。本研究项目的目的是通过计算机实验和分析GEOTAIL的波形数据来解决这些微观的非线性波动动力学问题。我们还在波形的统计研究中使用了独特的方法，如模式识别和常规的傅立叶变换。我们注意到了宽带静电噪声(BEN)、窄带静电噪声(NEN)、电子回旋加速器…的波形更多的谐波(ECH)和调幅的朗缪尔波。通过对这些波形的分析和计算机实验，我们考察了波浪动力学中的微观非线性过程，特别是本研究项目中本产生机制的发现具有非常重要的意义。我们首次发现BEN是由束-等离子体相互作用产生的静电孤立波构成的。通过计算机实验，我们还揭示了ESW是由束-等离子体不稳定性产生的BGK模的非线性解。为了对地震波进行统计分析，我们提出了一种利用位模式匹配的新方法，并成功地实现了地震波波形的自动提取。我们可以弄清楚电子激波传播与电子束传播之间的关系，以及电子激波宽度与局域德拜长度之间的关系。统计分析表明，与本研究中进行的计算机实验结果吻合较好。较少