Unsteady behavior of supercritical perpendicular shock waves in a multiple-ion-species plasma

Supercritical perpendicular shock waves propagating in a plasma containing electrons and two positive ions (i.e., protons and alpha particles) are studied using a one-dimensional electromagnetic hybrid code. It is found that, as the number density ratio of heavy ions to protons is increased, the shock with a moderately high Mach number becomes more dynamic and changes its structure periodically. In this paper, we present the simulation results of a perpendicular shock with proton Alfvén Mach number ∼ 9 and n _α /n _e = 0.1, where n _α and n _e are the number densities of alpha particles and electrons, respectively. We further discuss the parameter dependence of the non-stationary property of the shock structure.