Study of Energetic Particle's Acceleration Mechanism at Perpendicular Shock With Particle Simulation Results

Large amount of test particles＇ trajectories at perpendicular shock with magnetic turbulence are calculated. And the effect of shock strength and particles＇ initial energy to the average energy change per shock-crossing is also studied. Furthermore, the test particle＇s energy gain from Shock Drift Acceleration （SDA） under different conditions is analysed, too. In addition, a theoretical （1） formula △E=arnvivup（1-1/s） is given for SDA, which agrees very well with our simulation results. The results show that, although magnetic turbulence is included, particles would still be accelerated mainly by SDA at perpendicular shock, while the diffusive shock acceleration, based on the guiding center assumption, is not valid.