CAS Key Laboratory of Basic Plasma Physics, School of Earth and Space Sciences, University of Science and Technology of China, Hefei, Anhui 230026, China.
Phys Rev Lett. 2010 Apr 30;104(17):175003. doi: 10.1103/PhysRevLett.104.175003. Epub 2010 Apr 29.
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.
数值模拟预测，在 X 线附近延伸的电流片可能对二次磁岛不稳定，而这些磁岛会显著影响重联率。在这封信件中，我们首次提供了在离子扩散区中心附近存在这种二次磁岛的证据，这与在 X 线附近发生的二次磁岛不稳定性的作用一致。该磁岛在 z 方向被压扁，具有较强的核心磁场。在离子扩散区中发现具有各向异性或沿磁场方向双向通量的高能电子，并且在二次磁岛内高能电子通量的增强更为明显。
