The process of electron acceleration during collisionless magnetic reconnection

Two-dimensional particle-in-cell simulations are performed to study electron acceleration in collisionless magnetic reconnection. The process of electron acceleration is investigated by tracing typical electron trajectories. When there is no initial guide field, the electrons can be accelerated in both the X-type and O-type regions. In the X-type region, the electrons can be reflected back and enter the acceleration region several times before they leave the diffusion region. In this way, the electrons can be accelerated by the inductive electric field to high energy. In the O-type region, the trapped electrons can be accelerated when they are trapped in the magnetic island. When there is an initial guide field, the electrons can only be accelerated in the X-type region, and no obvious acceleration is observed in the O-type region. In the X-type region, the electrons are not demagnetized and they gyrate with the force of the guide field. Although no electron reflection is observed in this region, the acceleration efficiency can be enhanced through staying longer time in the diffusion region due to their gyration motion