Kinematic Collisionless Relaxation and Time Dependence of Supercritical Shocks with Alpha Particles

Upon crossing, the shock front ions begin to strongly gyrate due to the effect of the macroscopic magnetic and electric field. The strongly nongyrotropic downstream distributions gradually gyrotropize due to the gyrophase mixing. Kinematic collisionless relaxation has been successful in explaining the downstream magnetic oscillations in time-independent planar laminar shocks. Time dependence of supercritical shocks becomes more pronounced with the increase of the Mach number. While downstream gyrating distributions are still formed due to macroscopic fields, pressure balance can no longer be maintained throughout, causing time dependence. The presence of alpha particles enhances the destabilization of the shock.