Effects of Hall Current in the Driven Reconnection with Various Scales

In the driven reconnection process with various scales, the effect of Hall current is studied numerically using a Hall magnetohydrodynamics (MHD) code derived from a multi-step implicit scheme. In the cases with L_c/d_i ≤ 1.0 (L_c is the half-thickness of initial current layer, d_i is the ion inertial length), the features of Hall MHD reconnection are shown as follows: a quasi-steady single X-line reconnection is obtained, the B_y component with a quadrupolar structure is generated and the maximum reconnection rate is larger than 0.11. In the cases with L_c/d_i > 1.0, the effect of Hall current on the reconnection dynamics weakens and Hall MHD reconnection is gradually transformed into resistive MHD reconnection as L_c/d_i increases.