| 亚暴膨胀相近磁尾位形不稳定性模型Ⅰ．近磁尾位形不稳定性 |
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| 引用本文： | 濮祖荫,洪明华.亚暴膨胀相近磁尾位形不稳定性模型Ⅰ．近磁尾位形不稳定性[J].地球物理学报,1996,39(4):441-451. |
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| 作者姓名： | 濮祖荫 洪明华 |
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| 作者单位： | 1. 北京大学地球物理系，北京 100871;
2. 武汉大学空间物理系，武汉 430072;
3. 航天医学工程研究所，北京 100094;
4. 中国科学院空间科学与应用研究中心，北京 100080;
5. Max-Planck-Institute for Aeronomy, D-37189， Germany |
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| 基金项目： | 国家自然科学基金;国家教委博士点基金 |
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| 摘 要： | 用单流体和双流体ＭＨＤ近似，研究了近磁尾位形不稳定性（ＮＥＴＣ）．分析表明，ＮＥＴＣ可能存在两种漂移不稳定情况Ｃ１和Ｃ２与卫星观测资料对比显示，Ｃ２较容易在亚暴膨胀相前夕出现，它可以解释亚暴膨胀相期间磁场和等离子体扰动的特征周期、尾向传播速度、磁场扰动和等离子体压强扰动之间的位相关系，场向电流的周期性结构，西向涌浪头部的电子沉降和极光隆起等观测特性和现象．薄电流片的极端情况（Ｒｃ≈ｒｉ）不在本文的讨论范围之内．
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| 关 键 词： | 磁层亚暴 亚暴膨胀相 近磁尾漂移不稳定性 越尾电流中断 |
| 收稿时间： | 1995-08-23 |
A SUBSTORM EXPANSION MODEL BASED ON CONFIGURATION INSTABILITY OF THE NEAR-EARTHMAGNETOTAIL:I.CONFIGURATION INSTABILITY IN THE NEAR-EARTH MAGNETOTAIL |
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| PU ZU-YIN,HONG MING-HUA,WANG XIAN-MIN,CHEN ZU-XING,FU SUI-YAN,ZHONG QIU-GANG,WANG JING-PANG,LIU ZHEN-XING,A. KORTH,R. FRIEDEL,G. KREMSER.A SUBSTORM EXPANSION MODEL BASED ON CONFIGURATION INSTABILITY OF THE NEAR-EARTHMAGNETOTAIL:I.CONFIGURATION INSTABILITY IN THE NEAR-EARTH MAGNETOTAIL[J].Chinese Journal of Geophysics,1996,39(4):441-451. |
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| Authors: | PU ZU-YIN HONG MING-HUA WANG XIAN-MIN CHEN ZU-XING FU SUI-YAN ZHONG QIU-GANG WANG JING-PANG LIU ZHEN-XING A KORTH R FRIEDEL G KREMSER |
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| Institution: | 1. Department of Geophysics, Peking University, Beijing 100871, China;
2). Department of Space Physics, Wuhan University, Wuhan, 430072, China;
3. Institute of Sapce Medico-Engineering, Beijing 100094, China;
4. Center of Space Science & Applied Research, Academia Sinica, Beijing 100080, China;
5. Max-Planck-Institut fur Aeronomie, D-37189, Germany |
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| Abstract: | One-fluid and two-fluid MHD approaches are used to investigate configuration instability prior to onset of the substorm expansion phase in the near-Earth magnetotail. Completely identical results are obtained with these two methods. It is found that there are two instability criterions in the near-Earth tail: C1 and C2. In the limited case of,C1 and C2 are fulfiled, respectively, when β>2β1-2/r and β<2β1-2/γ,β1>1/γ,whereβrepresnets the ratio of the plasma pressure over the magnetic pressure,γ is the isentropic index, β1=2Lp/ Rc,Lp and Rc denote the scale length of the pressure gradient and the curvature radius of the magnetic field lines, respectively. Comparison of our theory with GEOS 2 observations indicates that C2 may easily be satisfied in the late growth phase,leading to disruption of the cross-tail current and the formation of the substorm current wedge. It is also shown that the development of near-Earth cenfiguration instability can explain a number of characteristic features of the substorm expansionphase. The extremely thin current sheet case with Rc≈ri should be studied with methods other than the MHD approximation. |
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| Keywords: | Magnetospheric substorm expansion phase Near-Earth magnetotail drift mode instability Cross-tail current disruption |
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