Evolution of ring current and radiation belt particles under the influence of storm‐time electric fields
Evolution of ring current and radiation belt particles under the influence of storm‐time electric fields
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DOI：
10.1029/2006ja012177
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发表时间：
2007-06
影响因子：
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通讯作者：
Y. Nishimura;A. Shinbori;T. Ono;M. Iizima;A. Kumamoto
中科院分区：
文献类型：
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作者：
Y. Nishimura;A. Shinbori;T. Ono;M. Iizima;A. Kumamoto
[1]利用Akebono/EFD资料研究了磁暴期间内磁层的电场和电位分布。利用这个电场，我们通过单粒子计算研究了环电流粒子的注入和辐射带电子的加速。在主相期间，晨昏电场在2 < L < 5的范围内增强，最大幅值在黄昏侧为6 mV/m，并确定了一个电位差为180 kV的双胞对流模式。赤道面上的对流模式是显着扭曲的黎明和黄昏部门的70千伏的大电位降，表明内磁层的大规模电场的内在来源。等离子体片离子由于强E × B漂移而聚集到内磁层的黄昏至午夜前扇区中的电场增强区。在40分钟内，离子以超过1个数量级的加速度被输送到约4 RE，保持第一绝热不变量。相对论电子的初始能量约为数百千电子伏，在5 RE被激发到超过100 keV，持续3小时。在不考虑径向扩散和等离子体波非绝热加速的情况下，再现了1990年10月9日CRRES卫星观测到的磁暴恢复阶段的能谱。这种加速过程可能是大尺度电场的不均匀性，它对应于电子绕地球沿着轨道的E × E项。
[1] Electric field and potential distributions in the inner magnetosphere during geomagnetic storms have been investigated using the Akebono/EFD data. Using this electric field, we study injection of ring current particles and acceleration of radiation belt electrons by single-particle calculations. During the main phase, the dawn-dusk electric field is intensified especially in a range of 2 < L < 5 with a maximum amplitude of 6 mV/m on the duskside, and a two-cell convection pattern with a potential difference of 180 kV is identified. The convection pattern on the equatorial plane is significantly distorted with a large potential drop of 70 kV on the dawn and dusk sectors, indicating an intrinsic source of large-scale electric field in the inner magnetosphere. The plasma sheet ions are gathered into the dusk to premidnight sector in the inner magnetosphere in the region of enhanced electric field due to the strong E × B drift. The ions are transported into around 4 RE with an acceleration of more than 1 order of magnitude within 40 min, conserving the first adiabatic invariants. Relativistic electrons with initial energy of some hundreds of kiloelectron volts at 5 RE are energized to more than 100 keV for 3 hours. The energy spectrum during the recovery phase of 9 October 1990 geomagnetic storm observed by the CRRES satellite is reproduced without the radial diffusion or nonadiabatic acceleration by plasma waves. It is possible that this acceleration process is the inhomogeneity of the large-scale electric field, which corresponds to the ∇ × E term along orbits of electrons around the Earth.