Comprehensive study on plasma waves in the magnetosphere

本课题主要研究的内容如下：1.电磁波的产生和传播，2。等离子体波活动与地磁活动的关系; 3.静电波的产生。在课题1中，我们研究的波之一是由Geotail航天器发现的极光千湄辐射（AMR）。我们用射线追踪法进行了数值计算，并将所得的传播特性与观测结果进行了比较。我们的研究表明，在极地大气中，AMR辐射与AKR（极光千米辐射）的区域相同。在第二个主题中，我们执行了Geotail和Equator-S卫星之间的合作。我们利用这两颗卫星观测了等离子体片结构的动态运动和时间变化，首次从多星观测中揭示了地磁场线的变薄效应和偶极化现象。 ...更多信息 ns。此外，我们还分析了低纬边界区的Geotail观测资料，发现等离子体从磁鞘向磁层的输运存在不同的机制。在课题3中，我们对在等离子体片边界层（PSBL）中观测到的静电孤立波（ESW）进行了统计分析。计算结果与计算机模拟的预期特征非常一致。该协议支持的模型，电子束不稳定性的非线性演化导致形成孤立的静电势结构，这是由计算机模拟提出的。我们还研究了NEN活动（窄带静电噪声）和电子之间的相关性。我们发现NEN活性与极性电子的存在密切相关。极向电子速度分布的结构导致电子速度空间空穴模的不稳定，这被认为是NEN的产生机制。少

The main topics which we focused on in this project are categorized as follows : 1. Generation and propagation of electromagnetic waves, 2. Relation of plasma wave activities to geomagnetic activities, and 3. Generation of electrostatic waves. In the topic 1, one of waves we investigated is the Auroral Myriametirc Radiation (AMR), which was discovered by Geotail spacecraft. We conducted the numerical calculation using the ray tracing method and compared obtained results on the propagation charcteristics with observational results. Our research shows that the AMR is radiated around the same region of AKR(Auroral Kilometoric Radiation) in the polar atmosphere. In the second topic, we performed the collaboration between Geotail and Equator-S satellites. We observed the dynamic motion and time variation of the plasma sheet structure using these two satellites and revealed the thinning effect and dipolalization of the geomagnetic field line first time from the multiple-spacecraft observatio … More ns. Further, we also examined the Geotail data which were observed in the low latitude boundary region and obtained that there exist different mechanisms which cause the plasma transportation from the magnetosheath into the magnetosphere. In the topic 3, we conducted the statistical analyses on the Electrostatic Solitary Waves (ESW), which are observed in the Plasma Sheet Boundary Layer (PSBL). The results are very consistent with the expected features of ESW by computer simulations. This agreement supports the model that the nonlinear evolution of electron beam instabilities lead to the formation of isolated electrostatic potential structures, which are proposed by computer simulations. We also examined the correlation between the NEN activities(Narrowband Electrostatic Noise)and electrons. We found the close relation between NEN activities and the existence of polar electrons. The structure of polar electron velocity distributions lead to destabilize the electron velocity space hole mode, which was proposed as the generation mechanism of NEN. Less