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Investigation of Magnetic Reconnection in Space Plasma

空间等离子体中磁重联的研究

基本信息

批准号：
07044105
负责人：
NISHIDA Atsuhiro
金额：
$ 3.46万
依托单位：
Institute of Space and Astronautical Science
依托单位国家：
日本
项目类别：
Grant-in-Aid for international Scientific Research
财政年份：
1995
资助国家：
日本
起止时间：
1995 至 1996
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-07044105/
关键词：
Reconnection Magnetotail Magnetic neutral line Slow-mode shock Plasmoid Substorm Ion beams Fast plasma flow GEOTAIL satellite slow-mode電磁流体波イオンサイクロトロン波

项目摘要

Magnetic reconnection processes have been studied in detail on the hasis of analysis of the GEOTAIL data obtained in the geomagnetic tail at distances of 10 to 30 Re away from the Earth. Collaborative studies with US satellites of WIND and POLAR and with Russian satellite Interball-Tail were highly useful to elucidate the reconnection processes in substorms. A number of important results have been brought forth, which have been (and will be) published in scientific journals. Some selected results are listed below.1.The GEOTAIL observations have revealed the kinetic structure of slow-mode shocks exising between the lobe-plasma sheet boundary in the geomagnetic tail. Based on detiled analysis of the ion distribution functions, it is found taht 3-20 % of the heating of cold ions passing through the slow-mode shock occurs in the foreshock region. Interaction with the electromagnetic ion cyclotron waves generated by the counterstreaming ion beams was suggested as a candidate of this heating … More .2.The GEOTAIL observations have found the existence of ion beams of the lobe origin streaming along the magnetic field lines deep inside plasmoids, as evidence of the plasmoid formation by magnetic reconnections. The existence of non-gyrotropic ion beams is also found in a region which is considered as near the diffusion region. These observational results agree well with those of computer simulations of magnetic reconnections.3.Based collaborative studies of GEOTAIL with WIND and POLAR satellites, it is found that the magnetic reconnection was initiated in the plasma sheet at distances of -25 Re downtail prior to a substorm onset, suggesting that the reconnections trigger substorms at least in some cases.4.Joint studies between GEOTAIL and Interball-Tail data have evidence that magnetic reconnections took place in the plasma sheet at distances between 13 and 28 Re downtail.5.Statistical analysis of fast plasma flows has revealed that magnetic reconnections occur around midnight to the duskside in the magnetotail at distances of 20 to 30 Re in association with substorm onset, and the reconnection region is widened in the dawndusk direction as it moves downtail. Less

在对距地球10~30 Re地磁尾的GEOTAIL数据进行分析的基础上，对磁重联过程进行了详细研究。与美国卫星 WIND 和 POLAR 以及俄罗斯卫星 Interball-Tail 的合作研究对于阐明亚暴中的重新连接过程非常有用。已经取得了许多重要成果，这些成果已经（并将）发表在科学期刊上。部分成果如下： 1.GEOTAIL观测揭示了地磁尾叶-等离子体片边界之间存在慢模激波的动力学结构。通过对离子分布函数的详细分析，发现冷离子经过慢模激波时的加热有3％～20％发生在前震区。与逆流离子束产生的电磁离子回旋波的相互作用被认为是这种加热的候选者……更多 .2.GEOTAIL 观测发现存在波瓣起源的离子束沿着等离子体团深处的磁场线流动，作为通过磁重联形成等离子体团的证据。在被认为接近扩散区域的区域中也发现了非回旋离子束的存在。这些观测结果与磁重联的计算机模拟结果非常吻合。3.基于GEOTAIL与WIND和POLAR卫星的合作研究，发现磁重联是在亚暴爆发前在距-25Re下尾处的等离子体片中启动的，这表明重联至少在某些情况下触发了亚暴。4.GEOTAIL和Interball-Tail数据之间的联合研究有证据表明磁重联发生在亚暴发生之前。 5.快速等离子体流的统计分析表明，磁重联发生在午夜左右到磁尾的黄昏侧，距离为20至30 Re，与亚暴的爆发有关，并且随着它向下移动，磁重联区域在黎明黄昏方向变宽。较少的