Favorable conditions for energetic electron acceleration during magnetic reconnection in the Earth's magnetotail
Favorable conditions for energetic electron acceleration during magnetic reconnection in the Earth's magnetotail
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DOI：
10.1029/2011ja016576
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发表时间：
2011-08
影响因子：
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通讯作者：
S. Imada;M. Hirai;M. Hoshino;T. Mukai
中科院分区：
文献类型：
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作者：
S. Imada;M. Hirai;M. Hoshino;T. Mukai
[1]我们利用GeoTail数据研究了地球磁层磁重联过程中高能电子加速的有利条件。我们在一些重联事件中发现了很强的高能电子加速。另一方面，其他重联事件显示出微弱的电子加速。为了讨论决定高能电子加速效率的重联特性，我们研究了GeoTail卫星在扩散区附近观测到的10个事件的重联特性。我们将重联特性与电子加速效率的关系分为三种类型：(1)良好的相关性(相关系数的绝对值|r|>；0.6)；(2)模糊相关性(0.6>；|r|>；0.3)；(3)无相关性(0.3>；|r|)。我们发现，离子加热、电子加热、电流片厚度、重联电场和会聚正态电场可以很好地关联在一起。离子/电子温度比、重联总磁能和重联率被归类为模糊相关。我们没有发现高能电子加速效率与流出速度的绝对值、平行于磁场的电流密度(霍尔电流系)以及卫星在地球磁层中的位置之间的任何关系。根据我们的分析，我们认为，在快速重联事件中，电子在薄电流片中被有效地加速。
[1] We have studied favorable conditions for energetic electron acceleration during magnetic reconnection in the Earth's magnetosphere using the Geotail data. We have found the strong energetic electron acceleration in some reconnection events. On the other hand, the other reconnection events show weak electron acceleration. To discuss what reconnection characteristics determine energetic electron acceleration efficiency, we have studied the reconnection characteristics for 10 events in which the Geotail satellite observed the vicinity of the diffusion region. We have classified the relationship between the reconnection characteristics and the electron acceleration efficiency into three types: (1) good correlation (absolute value of correlation coefficient ∣r∣ > 0.6); (2) ambiguous correlation (0.6 > ∣r∣ > 0.3); and (3) no correlation (0.3 > ∣r∣). We found that ion heating, electron heating, current sheet thickness, reconnection electric field, and converging normal electric field could be categorized into good correlation. Ion/electron temperature ratio, total amount of reconnected magnetic energy, and reconnection rate were classified in ambiguous correlation. We could not find any correlation between energetic electron acceleration efficiency and absolute value of outflow velocity, current density parallel to magnetic field (Hall current system), and satellite location in the Earth's magnetosphere. From our analysis we claimed that the electrons are efficiently accelerated in a thin current sheet during fast reconnection events.