University of New Hampshire, Durham, NH, USA.
Southwest Research Institute (SwRI), San Antonio, TX, USA.
Science. 2018 Dec 21;362(6421):1391-1395. doi: 10.1126/science.aat2998. Epub 2018 Nov 15.
Magnetic reconnection is an energy conversion process that occurs in many astrophysical contexts including Earth's magnetosphere, where the process can be investigated in situ by spacecraft. On 11 July 2017, the four Magnetospheric Multiscale spacecraft encountered a reconnection site in Earth's magnetotail, where reconnection involves symmetric inflow conditions. The electron-scale plasma measurements revealed (i) super-Alfvénic electron jets reaching 15,000 kilometers per second; (ii) electron meandering motion and acceleration by the electric field, producing multiple crescent-shaped structures in the velocity distributions; and (iii) the spatial dimensions of the electron diffusion region with an aspect ratio of 0.1 to 0.2, consistent with fast reconnection. The well-structured multiple layers of electron populations indicate that the dominant electron dynamics are mostly laminar, despite the presence of turbulence near the reconnection site.
磁重联是一种在许多天体物理环境中发生的能量转换过程，包括地球的磁层，在那里可以通过航天器进行原位研究。2017 年 7 月 11 日，四个磁层多尺度航天器在地球磁尾遭遇一个磁重联点，在那里重联涉及对称的流入条件。电子尺度的等离子体测量显示：(i) 超阿尔芬速度的电子喷流达到每秒 15000 公里；(ii) 电子蜿蜒运动和电场加速，在速度分布中产生多个新月形结构；(iii) 电子扩散区的空间尺寸为 0.1 到 0.2 的纵横比，与快速重联一致。结构良好的多层电子群体表明，尽管在重联点附近存在湍流，但主导电子动力学主要是层流。
