Hybrid Simulation of Ion Orbits in Magnetic Reconnection

Abstract

AbstractApplying a 2.5‐D hybrid simulation, we have studied the particle acceleration caused by magnetic reconnection. The results show that the reconnection process will not only heat all the particles, but also accelerate a few particles to comparatively high velocities (about 2.0vA). Such selective accelerating makes the velocity distribution of all particles changed from the Maxwellian distribution, to a shell or quasi‐shell distribution. In addition, this shape varies with the change of particle positions. In order to study the accelerating process occurring near the X‐type neutral point, we have observed the time‐variation of velocities and positions of selected particles. Among the particles flowed out inside the reconnection region, some are trapped in the magnetic mirror, with a convolution radius that outsteps the width of the reconnection region. These particles can thus construct the lowspeed part of the fluid near the boundary of outflow regions. On the other hand, there are three kinds of drifting trajectory for particles entering the reconnection region beside the X‐type neutral point: flee along the field lines, be trapped in the magnetic mirror, and traverse the local field lines. The ratios of particles undergoing the three kinds of trajectory are about 70%, 20%, 10%, respectively.