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

利用GEOTAIL卫星等离子体波形数据和粒子模型计算机实验，研究了地球磁层中观测到的非线性波动动力学。波形的分析使我们能够提取空间以及时间的非线性变化，在每个现象。特别是，在边界层，如磁重联区观察到的电子模式的波形分析是重要的等离子体加热，加速和扰动的关联。本研究计画的目的是透过电脑实验以及分析GEOTAIL的波形资料，来解决这些微观的非线性波浪动力学。在波形的统计研究中，我们还采用了独特的方法，如模式识别以及传统的傅立叶变换。重点研究了宽带静电噪声（BEN）、窄带静电噪声（NEN）、电子回旋噪声（E回旋噪声）等的波形 ...更多信息 谐波（ECH）和调幅朗缪尔波。通过波形分析和计算机实验相结合的方法，我们研究了波动动力学中的微观非线性过程，特别是BEN产生机制的发现在本研究项目中具有重要意义。首次发现BEN是由束流与等离子体相互作用产生的静电孤立波（ESW）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ESW波形进行统计分析，提出了一种基于位模式匹配的ESW波形自动提取方法，并成功地实现了ESW波形的自动提取。由此可以明确ESW与电子束的传播、ESW宽度与局域德拜长度之间的关系。统计分析表明，在本研究中进行的计算机实验中得到的结果有很好的一致性。少

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