The nature of Petschek-type reconnection
The nature of Petschek-type reconnection
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Petschek 型重联的本质
DOI：
10.1186/bf03353252
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发表时间：
2001
期刊：
影响因子：
--
通讯作者：
T. Forbes
中科院分区：
文献类型：
--
作者：
T. Forbes
Petschek重联机制是MHD方程的一个特殊解，仅在满足特殊条件时才适用，这一点并不总是被理解。具体地说，它要求进入重联区的流动在没有外部强迫的情况下自发地建立。当通过增强局部区域的电阻率来启动简单电流片中的重连时，满足该条件。这样一个过程破坏了电流片，并发射慢模波，慢模波变陡成Petschek预测的那种几乎关闭的冲击。当这些冲击向外传播时，电流片在扰动的原点处重新形成，并形成准定常的类Petschek结构。类似于Syrovatskii的结构，通过驱动一个流动朝向一个最初没有电流的正交x点来迫使重联，不太可能满足Petschek型重联所需的条件。
It is not always appreciated that Petschek’s reconnection mechanism is a particular solution of the MHD equations which applies only when special conditions are met. Specifically, it requires that the flow into the reconnection region be set up spontaneously without external forcing. This condition is satisfied when reconnection in a simple current sheet is initiated by enhancing the resistivity in a localized region. Such a process disrupts the current sheet and launches slow-mode waves which steepen into nearly switch-off shocks of the type predicted by Petschek. As these shocks propagate outwards, the current sheet reforms at the original point of the disturbance, and a quasi-steady Petschek-like configuration is set up. Syrovatskii-like configurations which force reconnection by driving a flow toward an initially current-free, orthogonal x-point are less likely to satisfy the conditions required for Petschek-type reconnection.