MHD simulation of magnetic reconnection and magnetic substorms

Magnetic reconnection based on the resistive and Hall MHD equations are reviewed. It is found from both theory and simulation that the impulsive reconnection can be achieved in the resistive and Hall MHD by imposing suitable boundary conditions. All results from resistive and Hall MHD indicate that reconnection processes contain two phases: slow growth phase and impulsive phase, and between them there is a sudden change of growth rate. However, the distribution and magnitude of the parallel electric field in the Hall MHD reconnection are much broader and larger than ones in the resistive MHD reconnection. Furthermore, nonlinear reconnection rate in the Hall MHD is nearly independent in the Lundquist number. The application of the impulsive magnetic reconnection to substorms in the magnetotail is presented.