A three‐dimensional hybrid simulation of magnetic reconnection

Abstract

We study magnetic reconnection in the magnetotail by a 3‐D hybrid simulation (ion particle, charge neutralizing massless electron fluid). Magnetic reconnection is initiated by putting anomalous resistivity localized in the plasma sheet. The resistive region is set up to have a finite dawn‐dusk extent so that 3‐D effects in the presence of ion particle dynamics are studied. Indeed, in the course of reconnection, plasma flow pattern and magnetic field configuration show highly asymmetric features in the dawn‐dusk direction due to ion kinetic responses. The initial dawn‐to‐dusk ion current is disrupted on the dawnside of the diffusion region, requiring electrons to flow into the diffusion region from the duskside of it to support the cross‐tail current, resulting in dawnward bending of field lines prior to reconnection. In contrast, reconnected field lines are transported by the reconnection jet which has substantial duskward flow component and eventually bend duskward.