Particle simulation of collisionless reconnection in three dimensions

Generation of anomalous resistivity and dynamical development of collisionless reconnection in the vicinity of a magnetically neutral sheet are investigated by means of a three-dimensional particle simulation. For no external driving source, two different types of plasma instabilities are excited in the current layer in the same way as the two-dimensional case. The lower hybrid drift instability is observed to grow in the periphery of the current layer, but it cannot penetrate into a high-beta region near the neutral sheet. Instead, a low-frequency electromagnetic (EM) instability is excited at the neutral sheet after saturation of the lower hybrid drift wave. Thus, the interaction between this EM wave and charged particles can cause an anomalous resistivity in the neutral sheet. When an external driving flow exists, collisionless reconnection is triggered by the particle kinetic effect and the anisotropic ion distribution is formed through the anomalous ion heating inside the current layer.