等离子体片离子分界线的模拟研究  

Simulation studies of plasma sheet ion boundary

作　　者：丁维贞[1,2] 曹晋滨[1,3] 曾立[3] 王艳[3] 杨俊英[3] 

机构地区：[1]中国科学院空间科学与应用研究中心,中国科学院空间天气学国家重点实验室,北京100190 [2]中国科学院研究生院,北京100049 [3]北京航空航天大学宇航学院,北京100191

出　　处：《地球物理学报》2010年第7期1505-1514,共10页Chinese Journal of Geophysics

基　　金：国家自然科学基金重点项目(40931054);国家重点基础研究发展计划(2006CB806305);空间天气学国家重点实验室专项基金资助

摘　　要：等离子体片离子向内磁层的渗透在亚暴和磁暴过程中都起到了重要作用.以往对于等离子体片离子向内磁层的渗透都是通过固定磁矩的磁层离子漂移轨道理论来进行的.本文将过去的(U,B)空间中固定磁矩的磁层离子漂移轨道理论扩展为固定能量的磁层离子漂移轨道理论,讨论了等离子体片质子在向地球输运过程中,不同能量的质子开放轨道和封闭轨道的分界线的特性,及其随Kp指数的变化.在高能端,随着能量的升高,等离子体片质子分界线地心距离逐渐增大,且分界线的晨侧地心距离远远大于昏侧的地心距离.在低能端,随着质子能量的降低,质子分界线地心距离逐渐增大,且其分界线的昏侧地心距离要大于晨侧的地心距离.模拟结果还显示随着Kp指数的增强,等离子体片中不同能量的质子分界线都向地球移动.但在低能端和高能端,质子分界线的行为是不一样的.在低能端,随着Kp指数的增大,质子内边界形状基本保持不变.但在高能端,随着Kp指数的增大,质子内边界形状也将发生变化.在E=20 keV,Kp=6和E=10 keV,Kp=3两种情况,质子分界线甚至出现了两个分离的区域,一个是环绕地球的封闭轨道区域,一个是晨侧孤立的锥型区域.等离子体片能量为E的质子的内边界就是具有不同磁矩的Alfven层上能量为E的点的连线.TC-1热离子谱仪对等离子体片离子内边界的观测显示模拟结果与观测结果符合得很好.The injection of plasma sheet ion to inner magnetosphere plays an important role during the time of magnetic sub-storm and storm periods. In the past, researches of such injection were all processed by the method of drift path theory of certain magnetic moment particles. In this article, we will extend the past certain magnetic moment magnetosphere particle drift path theory in （U,B） coordinate to certain energy magnetosphere particle drift path theory. Because particle＇s drift orbit is associated with its charge, we will take proton as an example. Then we will discuss the characters of different energy particles＇ boundary between their open and close drift path and its variation with I（p index during their transportation to the Earth. In high energy situation, the radial distance to the Earth of plasma sheet ionsr boundary will with their energy, and the distance in dawn side is much larger than that in dusk side. B energy situation, such thing will completely change. The radial distance will decrease energy and the radial distance in dusk side will be larger than that in dawn side. Our si increase ut in low with ion mulation results also show that with the increase of Kp index, all boundaries of various energy particles in the plasma sheet will move towards the Earth. But performances of ion boundaries in high and low situations are different. To low energy situation, the inner boundary shape of ion almost keeps constant with the increase of Kp index. To high energy situation, its shape will change remarkably with Kp index. In two extreme cases, that is, E=20 keV, Kp=6 and E=10 keV, Kp=3, the ion boundaries even show two different regions, one is the closed circling Earth region and the other is the isolated tapered region in dawn side. The boundary of plasma sheet certain-energy-E particles is just the connection of energy-E point in various magnetic moments Alfven layer.

关 键 词：等离子体片离子分界线 (U  B)空间 KP指数 Alfven层 

分 类 号：P353[天文地球—空间物理学]