Basic physical mechanism of reconnection development and magnetic loop dynamics
Basic physical mechanism of reconnection development and magnetic loop dynamics
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重联发展和磁环动力学的基本物理机制
DOI：
10.1029/1998ja900181
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发表时间：
1999
影响因子：
--
通讯作者：
M. Ugai
中科院分区：
文献类型：
--
作者：
M. Ugai
通过计算机模拟研究了各种物理条件下非线性重联和磁回路发展的基本特征。在一个长电流片系统中，由一个小扰动引发的磁重联建立起来，并在（左）壁边界附近形成一个磁回路。对于自发快速重联模型，如果重联点远离壁面，则建立了准稳态对称的快速重联机制，而对等离子体参数没有明显的依赖性。一对静止的慢激波之间的超音速重联喷流与环碰撞，并在环顶前方产生一个强的快激波。当重联点非常靠近壁面时，快激波非常弱，很快衰减，而且快重联过程变得不对称，因为从环顶反射的波对X点有显著的影响。对于均匀电阻率模型，磁重联进行得慢得多，没有明确的快速冲击形成在环的顶部。X中性点不稳定，但塌陷成一个长扩散区，扩散区的伸长变得更迅速，为较小的电阻率。在这种情况下，磁能转换是由欧姆加热，而它是由大规模的电动机（慢冲击）效应的自发快速重联模型。
The basic features of nonlinear reconnection and magnetic loop development are studied by computer simulations in a wide variety of physical situations. Initiated by a small disturbance in a long current sheet system, magnetic reconnection builds up, and a magnetic loop is formed near the (left) wall boundary. For the spontaneous fast reconnection model, if the reconnection site is far from the wall, the quasi-steady and symmetric fast reconnection mechanism is set up without any significant dependence on plasma parameters. The supersonic reconnection jet between a pair of standing slow shocks collides with the loop and gives rise to a strong fast shock ahead of the loop top. When the reconnection site is very close to the wall, the fast shock is much weaker and soon decays, and the fast reconnection process becomes asymmetric since the waves, reflected from the loop top, notably influence the X point. For the uniform resistivity model, magnetic reconnection proceeds much more slowly with no definite fast shock formation at the loop top. The X neutral point is not stable but collapses into a long diffusion region, and the elongation of the diffusion region becomes more rapid for the smaller resistivity. In this case, the magnetic energy conversion is performed by the Ohmic heating, whereas it is by the large-scale motor (slow shock) effect for the spontaneous fast reconnection model.