Two-dimensional compressible magnetohydrodynamic simulation of the driven reconnection process

A two-dimensional compressible magnetohydrodynamic code is developed to provide simulations of the driven reconnection process in conducting plasma. For a fixed value of the plasma inflow at the boundary (Alfvénic Mach number M_A = 0.15) and a ratio of 2:1 for the two sides of the simulation box, the dependence of the reconnection effect as a function of time on the magnetic Reynolds number is investigated by examining a range of R_m value (400-2500). The size of the current sheet is generally found to cover the horizontal length of the whole simulation box. It is found that as R_m increases, the plasma system will evolve from a configuration of one single X-line formation to a multiple X-line formation. Unlike the former situation, the multiple X-line formation is characterized by quasiperiodic generation of secondary magnetic islands (or plasmoids) of high temperature and dense mass. These two states are separated by a critical value of R_m* = 2000 for the plasma parameters considered. The occurrence of the flux tube transfer events (FTE's) at the magnetopause might be related to the nonstationary driven reconnection with high R_m value as found here.