三维非线性撕裂模耦合和快速磁场重联

THREE DIMENSIONAL NONLINEAR COUPLING OF TEARING MODES AND FAST MAGNETIC RECONNECTION

基于三维不可压缩电阻性ＭＨＤ方程，在长柱形位型下，数值研究了电阻撕裂模不稳定性所引起的磁场重联过程．研究结果表明，撕裂模的非线性相互作用和耦合，将产生许多模式的强烈解稳和导致快速的磁场重联．这一过程的进一步发展，导致具有螺旋形结构、不同模式的磁岛磁力线重叠，从而引起较大区域内的磁场各态经历和磁力线随机走向，形成撕裂模湍动；该湍动将会产生较大的反常电阻，反过来可以进一步加速撕裂模的非线性发展．这种自激过程，有助于理解日冕中的快速磁重联，并可作为一种可能的太阳耀斑机制．

In this paper, magnetic reconnection caused by the tearing-mode instability ina long and thin cylindrical geometry is numerically studied in the framework ofthree-dimentional incompresible resistive MHD theory. The results show that thenonlinear coupling of tearing modes with low ploidal mode numbers leads to therapid destabilization of the modes with higher ploidal mode numbers and to fastmagnetic reconnection. Furthermore, tearing mode turbulence is generated and theanomalies will be produced. The anomalous resistivity can quicken the growth ofthe tearing-mode instability and accopanying reconnection process. It is suggestedthat fast magnetic reconnection as a mechanism for the solar flares may be associated with this self-excited process caused by the nonlinear coupling of tearingmode instabilities in the solar corona.