In situ observations of a secondary magnetic island in an ion diffusion region and associated energetic electrons.
In situ observations of a secondary magnetic island in an ion diffusion region and associated energetic electrons.
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DOI：
10.1103/physrevlett.104.175003
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发表时间：
2010-04
影响因子：
8.6
通讯作者：
Rongsheng Wang;Q. Lu;A. Du;Shui Wang
中科院分区：
文献类型：
--
作者：
Rongsheng Wang;Q. Lu;A. Du;Shui Wang
数值模拟预测，扩展的电流片可能对X线附近的二次磁岛不稳定，这些磁岛会显著影响重联率。在这封信中，我们首次提出了在离子扩散区中心附近存在这种次生岛的证据，这与发生在X线附近的次生岛不稳定性的作用是一致的。岛在z方向上被压扁，核心磁场很强。在离子扩散区发现具有各向异性或场定向双向通量的高能电子，并且在二次岛内部高能电子通量的增强更为明显。
Numerical simulations have predicted that an extended current sheet may be unstable to secondary magnetic islands in the vicinity of the X line, and these islands can dramatically influence the reconnection rate. In this Letter, we present the first evidence of such a secondary island near the center of an ion diffusion region, which is consistent with the action of the secondary island instability occurring in the vicinity of the X line. The island is squashed in the z direction with a strong core magnetic field. Energetic electrons with anisotropic or field-aligned bidirectional fluxes are found in the ion diffusion region, and the enhancement of energetic electron fluxes is more obvious inside the secondary island.