Effects of Magnetic Shear and Thermodynamic Asymmetry on Spontaneous Magnetohydrodynamic Reconnection
Effects of Magnetic Shear and Thermodynamic Asymmetry on Spontaneous Magnetohydrodynamic Reconnection
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DOI：
10.3847/1538-4357/ac729f
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发表时间：
2022-06
期刊：
影响因子：
--
通讯作者：
S. Nitta;K. Kondoh
中科院分区：
文献类型：
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作者：
S. Nitta;K. Kondoh
利用二维磁流体动力学模拟研究了广义情况下（关于电流片和磁剪切具有热力学不对称性）磁重联的自发演化。我们专注于时间演化的渐近状态，即，自相似扩展阶段。(1)一个长的快模式冲击产生在前面的较短的等离子体团在剪切无磁不对称的情况下，然而，剪切的磁分量削弱了冲击。这种快速冲击波可能是粒子加速场。(2)较短的等离子体团侧等离子体浸润较长的等离子体团横跨电流片。然后，来自电流片两侧的等离子体在较长的等离子体团中共存于相同的磁力线上。这可导致有效的等离子体混合。(3)热力学不对称性和磁剪切使重联率大幅度降低了许多数量级。
The spontaneous evolution of magnetic reconnection in generalized situations (with thermodynamic asymmetry regarding the current sheet and magnetic shear) is investigated using a two-dimensional magnetohydrodynamic simulation. We focus on the asymptotic state of temporal evolution, i.e., the self-similarly expanding phase. (1) A long fast-mode shock is generated in front of the shorter plasmoid as in the shear-less thermodynamically asymmetric case; however, the sheared magnetic component weakens the shock. This fast shock may work as a particle acceleration site. (2) The shorter plasmoid-side plasma infiltrates the longer plasmoid across the current sheet. Then, the plasmas from both sides of the current sheet coexist on the same magnetic field lines in the longer plasmoid. This may result in efficient plasma mixing. (3) The thermodynamic asymmetry and magnetic shear drastically decrease the reconnection rate in many orders of magnitude.