Nonlinear variational method for predicting fast collisionless magnetic reconnection
Nonlinear variational method for predicting fast collisionless magnetic reconnection
复制标题
预测快速无碰撞磁重联的非线性变分方法
DOI：
10.1088/0029-5515/53/6/063024
复制
发表时间：
2013
期刊：
影响因子：
3.3
通讯作者：
M. Yagi and N. Aiba
中科院分区：
文献类型：
--
作者：
M. Hirota;P. J. Morrison;Y. Ishii;M. Yagi and N. Aiba
使用冷离子和电子的双流体模型研究了无碰撞等离子体中的快速磁重联机制，以了解托卡马克放电中的锯齿塌陷。使用具有非线性位移图的能量原理来分析估计由电子惯性引起的撕裂模式的爆炸增长。发现非线性区域（岛宽度超过电子集肤深度）中势能的下降比线性区域更陡，从而导致加速重联。这种流体位移释放的势能会导致不稳定的强对流流动，而高温托卡马克等离子体中的小耗散效应不会减弱这种对流流动。板坯几何形状的直接数值模拟证实了非线性增长的理论预测。
A mechanism for fast magnetic reconnection in collisionless plasma is studied for understanding sawtooth collapse in tokamak discharges using a two-fluid model for cold ions and electrons. Explosive growth of the tearing mode enabled by electron inertia is analytically estimated using an energy principle with a nonlinear displacement map. Decrease in the potential energy in the nonlinear regime (where the island width exceeds the electron skin depth) is found to be steeper than in the linear regime, resulting in accelerated reconnection. Release of potential energy by such a fluid displacement leads to unsteady and strong convective flow, which is not damped by the small dissipation effects in high-temperature tokamak plasmas. Direct numerical simulation in slab geometry substantiates the theoretical prediction of the nonlinear growth.