2-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 (Alfvenic 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.