Dependence of fast magnetic reconnection on electrical resistivity in an isolated current-sheet system

Computer simulation shows that, initiated by a resistive disturbance, the rarefaction of the current-sheet plasma and the subsequent remarkable thinning of the current-sheet region occur; once the fast reconnection builds up, the plasma density is extremely rarefied near the neutral point. The development of fast reconnection provides a situation favorable to the occurrence of a current-driven instability. The energy conversion rate associated with the fast reconnection is found to have a weak dependence on the magnetic Reynolds number Rm0 and tends to scale as (log10 Rm0)−1 for large Rm0. These results come from the fact that for larger Rm0 the diffusion region that is spontaneously established has a smaller width and hence a larger current density to compensate for the smaller magnitude of electrical resistivity. Effective energy conversion can be realized even in the presence of rigid walls.