Orientation and Stability of Asymmetric Magnetic Reconnection X Line
Orientation and Stability of Asymmetric Magnetic Reconnection X Line
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DOI：
10.1029/2018ja025410
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发表时间：
2018-05
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通讯作者：
Yi‐Hsin Liu;Michael Hesse;Tak Chu Li;M. Kuznetsova;Ari Le
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作者：
Yi‐Hsin Liu;Michael Hesse;Tak Chu Li;M. Kuznetsova;Ari Le
使用三维（3-D）粒子模拟研究了非对称几何中重联x线的取向和稳定性。我们在一个大的模拟域的中心启动重连，以尽量减少边界效应。所得到的x线具有足够的自由度来沿着沿着最佳取向发展，并且它保持层流。伴随的二维模拟表明，这种x线方向使重新连接率最大化。非共沸压力张量的发散打破了冻结条件，与其二维对应物一致。然后，我们设计了三维模拟，其中一个维度很短，以固定x线方向，但足够长，以允许增长最快的斜撕裂模式的增长。这个数值实验表明，重联往往辐射二次倾斜撕裂模式，如果它是外部（全球）被迫进行沿着的取向不赞成的本地物理。斜结构的发展容易导致小周期系统内部的湍流。
The orientation and stability of the reconnection x line in asymmetric geometry is studied using three‐dimensional (3‐D) particle‐in‐cell simulations. We initiate reconnection at the center of a large simulation domain to minimize the boundary effect. The resulting x line has sufficient freedom to develop along an optimal orientation, and it remains laminar. Companion 2‐D simulations indicate that this x line orientation maximizes the reconnection rate. The divergence of the nongyrotropic pressure tensor breaks the frozen‐in condition, consistent with its 2‐D counterpart. We then design 3‐D simulations with one dimension being short to fix the x line orientation but long enough to allow the growth of the fastest growing oblique tearing modes. This numerical experiment suggests that reconnection tends to radiate secondary oblique tearing modes if it is externally (globally) forced to proceed along an orientation not favored by the local physics. The development of oblique structure easily leads to turbulence inside small periodic systems.