Reconnection from a turbulence perspective
Reconnection from a turbulence perspective
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DOI：
10.1063/1.5128376
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发表时间：
2019-11
影响因子：
2.2
通讯作者：
Subash Adhikari;M. Shay;T. Parashar;P. Pyakurel;W. Matthaeus;D. Godzieba;J. Stawarz;J. Eastwood;J. Dahlin
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文献类型：
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作者：
Subash Adhikari;M. Shay;T. Parashar;P. Pyakurel;W. Matthaeus;D. Godzieba;J. Stawarz;J. Eastwood;J. Dahlin
使用2.5D动力学粒子在细胞（PIC）模拟的光谱特性与层流，反平行重联检查。重连率和能谱都表现出三个不同的阶段：重连率增长的起始阶段，准稳定阶段和重连率和能谱都下降的下降阶段。在稳定阶段，能谱表现出近似的双幂律行为，在小于逆离子惯性长度的波数处具有接近-5/3的斜率，并且对于高达逆电子惯性长度的较大波数，斜率陡于-8/3。这种行为与柯尔莫哥洛夫能量级联一致，并意味着层流重联可能从根本上是一个能量级联过程。与这个想法一致的是，重联率表现出粗略的相关性与能量谱在波数附近的离子惯性长度的倒数。2D频谱是强各向异性的，其中大部分能量与垂直于电流片的波矢量方向相关联。重连的作用是使能谱各向同性，在模拟结束时将谢巴林角从初始值70度减小到约48度（接近各向同性）。
The spectral properties associated with laminar, anti-parallel reconnection are examined using a 2.5D kinetic particle in cell (PIC) simulation. Both the reconnection rate and the energy spectrum exhibit three distinct phases: an initiation phase where the reconnection rate grows, a quasi-steady phase, and a declining phase where both the reconnection rate and the energy spectrum decrease. During the steady phase, the energy spectrum exhibits approximately a double power-law behavior, with a slope near -5/3 at wavenumbers smaller than the inverse ion inertial length, and a slope steeper than -8/3 for larger wavenumbers up to the inverse electron inertial length. This behavior is consistent with a Kolmogorov energy cascade and implies that laminar reconnection may fundamentally be an energy cascade process. Consistent with this idea is that the reconnection rate exhibits a rough correlation with the energy spectrum at wave numbers near the inverse ion inertial length. The 2D spectrum is strongly anisotropic with most energy associated with the wave vector direction normal to the current sheet. Reconnection acts to isotropize the energy spectrum, reducing the Shebalin angle from an initial value of 70 degrees to about 48 degrees (nearly isotropic) by the end of the simulation.