The effects of strong temperature anisotropy on the kinetic structure of collisionless slow shocks and reconnection exhausts. Part II: Theory
The effects of strong temperature anisotropy on the kinetic structure of collisionless slow shocks and reconnection exhausts. Part II: Theory
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强温度各向异性对无碰撞慢激波和重联排气动力学结构的影响。
DOI：
10.1063/1.3627147
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发表时间：
2011
期刊：
影响因子：
--
通讯作者：
M. Swisdak
中科院分区：
文献类型：
--
作者：
Yi‐Hsin Liu;J. Drake;M. Swisdak
对无碰撞斜向传播慢激波的模拟表明，存在与临界温度各向异性相关的转变，即δ =1-μ_0（P_parallel-P_vertical）/ B^2 = 0.25（Liu，Drake and Swisdak（2011））。本文基于各向异性流体理论，特别是各向异性导数非线性薛定谔-伯格斯方程，提出了对这种现象的解释，并给出了下游逆流离子能量封闭的直观模型。0.25的各向异性值是重要的，因为它与慢模式和中间模式的简并点密切相关，并且对应于在复合慢激波（SS）/旋转不连续（RD）波内部发生的共面到非共面过渡的下限。这项工作意味着，它是一对复合SS/RD波，约束流出的磁场重联，而不是一对关闭慢冲击Petschek的模型。这一事实可能解释了Petschek重连相关的关闭慢冲击的现场观测的罕见性。
Simulations of collisionless oblique propagating slow shocks have revealed the existence of a transition associated with a critical temperature anisotropy epsilon=1-mu_0(P_parallel-P_perpendicular)/ B^2 = 0.25 (Liu, Drake and Swisdak (2011)). An explanation for this phenomenon is proposed here based on anisotropic fluid theory, in particular the Anisotropic Derivative Nonlinear-Schrodinger-Burgers equation, with an intuitive model of the energy closure for the downstream counter-streaming ions. The anisotropy value of 0.25 is significant because it is closely related to the degeneracy point of the slow and intermediate modes, and corresponds to the lower bound of the coplanar to non-coplanar transition that occurs inside a compound slow shock (SS)/rotational discontinuity (RD) wave. This work implies that it is a pair of compound SS/RD waves that bound the outflows in magnetic reconnection, instead of a pair of switch-off slow shocks as in Petschek's model. This fact might explain the rareness of in-situ observations of Petschek-reconnection-associated switch-off slow shocks.