Contribution of the Hall current effect in the substorm current system

霍尔电流效应在亚暴流系统中的贡献

• 批准号: 12640431
• 负责人: NAGAI Tsugunobu
• 金额: $ 2.3万
• 依托单位: Tokyo Institute of Technology
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 2000
• 资助国家: 日本
• 起止时间: 2000 至 2002
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-12640431/
• 关键词: magnetosphere; substorm; field-aligned current; MHD; the Hall current system; magnetotail; The magnetosphere-ionosphere coupling; reconnection; ホール効果

In magnetic reconnection in the thin plasma sheet of the Earth's magnetotail, inflow electrons flow with the magnetic field line to the diffusion region, whereas inflow ions cannot reach the diffusion region and rest around a distance of the ion inertial length. The relative motion of the electrons and ions results in electric currents, that is, the Hall currents. The Hall currents can enhance the reconnection rate, so that it is important to evaluate the effects of the Hall currents in magnetic reconnection in observations as well as in simulations. We have investigated the plasma and magnetic field structure near the magnetic reconnection region in the magnetotail with the Geotail spacecraft. We have demonstrated the existence of the four Hall current loops with direct measurements of current density and with the resulting magnetic field By variations. We have firmly established that the outward currents in the outermost plasma sheet are carried with low-energy inflowing electrons. The inward currents exist in the adjacent region, just inside of the outward currents. Furthermore, the resulting By deflection is confined into the thin layer in the plasma sheet/tail lobe boundary. Hence, each current loop has the thin double-sheet current structure. With simulations, we have deduced the thickness of the double-sheet current structure and have found that its thickness is of the order of ion inertial length.

在地球磁尾的薄等离子体片的磁重联中，流入的电子沿着磁力线流向扩散区，而流入的离子不能到达扩散区，并停留在离子惯性长度的一段距离附近。电子和离子的相对运动产生电流，即霍尔电流。霍尔电流可以提高重联速率，因此在观测和模拟中评估霍尔电流对磁重联的影响是很重要的。我们用GeoTail航天器研究了磁尾磁重联区附近的等离子体和磁场结构。我们已经证明了四个霍尔电流环的存在，直接测量了电流密度，并通过变化产生了磁场。我们已经坚定地确定，最外层的等离子体片中的外向电流携带着低能量的流入电子。内向电流存在于邻近区域，就在外向电流的内部。此外，偏转导致的偏转被限制在等离子体片/尾瓣边界的薄层中。因此，每个电流回路都具有薄的双片电流结构。通过模拟，我们推导了双片电流结构的厚度，发现它的厚度是离子惯性长度的量级。

项目成果

Y. Yamade, M. Fujimoto, N. Yokokawa and M. S. Nakamura: "Field-aligned currents generated in magnetotail reconnection : 3D Hall-MHD simulations"Geophysical Research Letters. 27. 1091-1094 (2000)

Y. Yamade、M. Fujimoto、N. Yokokawa 和 M. S. Nakamura：“磁尾重联中产生的场对准电流：3D 霍尔 MHD 模拟”地球物理研究快报。

Y.Yamade, M.Fujimoto, N.Yokokawa, M.S.Nakamura: "Field-aligned currents generated in magnetotail reconnection : 3D Hall-MHD simulations"Geophysical Research Letters. 27. 1091-1094 (2000)

Y.Yamade、M.Fujimoto、N.Yokokawa、M.S.Nakamura：“磁尾重联中产生的场对准电流：3D 霍尔 MHD 模拟”地球物理研究快报。

T. Nagai, I. Shinohara, M. Fujimoto, M. Hoshino, Y. Saito, S. Machida, and T. Mukai: "Geotail observations of the Hall current system : Evidence of magnetic reconnection in the magnetotail"Journal of Geophysical Research. 106. 25929-25949 (2001)

T. Nagai、I. Shinohara、M. Fujimoto、M. Hoshino、Y. Saito、S. Machida 和 T. Mukai：“霍尔电流系统的 Geotail 观测：磁尾磁重联的证据”地球物理研究杂志

T. Nagai, M. S. Nakamura, I. Shinohara, M. Fujimoto, Y. Saito, and T. Mukai: "Counterstreaming ions as evidence of magnetic reconnection in the recovery phase of substorm at the kinetic level"Physics of Plasmas. 9. 3705-3711 (2002)

T. Nagai、M. S. Nakamura、I. Shinohara、M. Fujimoto、Y. Saito 和 T. Mukai：“逆流离子作为亚暴恢复阶段动力学层面磁重联的证据”等离子体物理学。

T.Nagai, H.J.Singer, T.Mukai, T.Yamamoto, Kokubun: "Dvelopment of substorms in the near-Earth tail"Advances in Space Research. 25. 1651-1662 (2000)

T.Nagai、H.J.Singer、T.Mukai、T.Yamamoto、Kokubun：“近地尾部亚暴的发展”空间研究进展。