Computer simulations of field‐aligned currents generated by fast magnetic reconnection in three dimensions
Computer simulations of field‐aligned currents generated by fast magnetic reconnection in three dimensions
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DOI：
10.1029/91ja01792
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发表时间：
1991-12
影响因子：
--
通讯作者：
M. Ugai
中科院分区：
文献类型：
--
作者：
M. Ugai
MHD模拟研究了与快速重联发展相关的电流系统的三维演变。初始平衡是一个一维反平行磁场，中间有电流片（或等离子体片）。快速重联是由局部电阻率引发的，并在电流片的有限区域内自发发展，导致阿尔芬等离子体射流。在等离子体喷射之前，等离子体片被明显压缩，形成一个膨胀和传播的等离子体流。在快速重联区，等离子体发生明显的稀薄，使等离子体流收敛，而在等离子体流中，等离子体被压缩，使等离子体流发散。由此产生的速度剪切引起沿等离子体边界的磁剪切，这与沿零级磁场的（正）场对准电流直接相关。因此，场对准电流就像一个沿着等离子体流边界延伸的管一样形成，并且随着等离子体在等离子体流中的压缩变大，它也变大。三维重联的快速发展引起了整个电流系统的剧烈变化，从而产生了电流的再分配。
MHD simulations have studied the evolution of an electric current system associated with fast reconnection development in three dimensions. The initial equilibrium is a one-dimensional antiparallel magnetic field with a current sheet (or plasma sheet) in the middle. Fast reconnection is initiated by a localized resistivity and spontaneously develops in a finite region of the current sheet, leading to an Alfvenic plasma jet. Ahead of the plasma jet the plasma sheet is notably compressed, forming a plasmoid which swells and propagates. In the fast reconnection region, notable plasma rarefaction occurs so that the plasma flow converges, whereas in the plasmoid, plasma is compressed so that the plasma flow diverges. The resulting velocity shear gives rise to a magnetic shear along the plasmoid boundary, which is directly related to a (positive) field-aligned current along the zero-order magnetic field. The field-aligned current is thus formed like a tube extending along the plasmoid boundary, and it becomes larger as the plasma compression in the plasmoid becomes larger. The fast reconnection development in three dimensions causes a drastic change in the overall current system to generate a redistribution of current.