Acceleration Mechanism Of Charged Particles In Collisionless Magnetic Reconnection Of Sub-Alfvenic Shear Flow

In this paper,the acceleration mechanism of charged particle in collisionless magnetic reconnection of sub-Alfvenic shear flow in the framework of compressible Hall MHD is studied and analyzed by means of numerical simulation,and the physical figure of particle acceleration is given.We find that there is a widespread particle acceleration generated by vortex electric field(induced electric field)in collisionless magnetic reconnection of sub-Alfvenic shear flow.For judging the strength of the particle acceleration generated by vortex electric field an index ? / is defined by us.The motion characteristics of charged particles under the index are further analyzed,we not only find that the region of 0 in the electromagnetic field can accelerate the particles,but also find that the region of 0 can attract charged particles to move to its core region,and the region of 0 can effectively repulse charged particles.By analyzing the slow shock generated by shear flow,we find that strong decelerating vortex electric field appears in the upstream of slow shock wave,charged particles moving upstream are blocked,strong accelerating vortex electric field appears in the downstream of shock,and magnetic mirror configuration will be formed at the shock surface,so charged particles moving downstream of shock wave will be confined to the magnetic mirror configuration at the shock surface and be accelerated by the vortex electric field,that is an effective mechanism for charged particles to be continuously accelerated and obtain high energy.We have studied the particle acceleration in the magnetic island and the accumulation area of magnetic,and found that not only the acceleration by vortex electric field but also the charged particle acceleration caused by the interaction of particle diffusion and vertical electric field in the secondary magnetic island;the structure of magnetic island can effectively restrain charged particles and make them repeatedly accelerate;the magnetic mirror configuration can be formed near the current sheet in the magnetic accumulation area,which can effectively accelerate the charged particles,the confined charged particles can obtain high kinetic energy in a very small area under the action of a weak vortex electric field.