Wang Shimou, Wang Rongsheng, Lu Quanming, Fu Huishan, Wang Shui
CAS Key Laboratory of Geospace Environment, Department of Geophysics and Planetary Science, University of Science and Technology of China, Hefei, 230026, China.
CAS Center for Excellence in Comparative Planetology, Hefei, China.
Nat Commun. 2020 Aug 7;11(1):3964. doi: 10.1038/s41467-020-17803-3.
Magnetic reconnection is a fundamental plasma process, by which magnetic energy is explosively released in the current sheet to energize charged particles and to create bi-directional Alfvénic plasma jets. Numerical simulations predicted that evolution of the reconnecting current sheet is dominated by formation and interaction of magnetic flux ropes, which finally leads to turbulence. Accordingly, most volume of the reconnecting current sheet is occupied by the ropes, and energy dissipation occurs via multiple relevant mechanisms, e.g., the parallel electric field, the rope coalescence and the rope contraction. As an essential element of the reconnecting current sheet, however, how these ropes evolve has been elusive. Here, we present direct evidence of secondary reconnection in the filamentary currents within the ropes. The observations indicate that secondary reconnection can make a significant contribution to energy conversion in the kinetic scale during turbulent reconnection.
磁重联是一种基本的等离子体过程，通过该过程磁能在电流片中爆发式释放，为带电粒子提供能量并产生双向阿尔文等离子体喷流。数值模拟预测，重联电流片的演化主要由磁通绳的形成和相互作用主导，最终导致湍流。因此，重联电流片的大部分体积被磁通绳占据，能量耗散通过多种相关机制发生，例如平行电场、磁通绳合并和磁通绳收缩。然而，作为重联电流片的一个基本要素，这些磁通绳如何演化一直难以捉摸。在此，我们给出了磁通绳内丝状电流中二次重联的直接证据。观测结果表明，二次重联在湍流重联期间的动力学尺度能量转换中可做出重大贡献。
