Ion Motions in Magnetosonic Shock Waves with Relativistic Propagation Speeds

Abstract

Ion motions in shock waves propagating perpendicular to a magnetic field are studied through theory and simulation; the shocks with relativistic propagation speeds are considered. In such shocks the longitudinal electric fields are less important than in nonrelativistic ones. From the analysis of ion orbits it is found that ion velocities parallel to the wave front can be comparable to the shock propagation speed v sh in the pulse region. Expressions for ion energies, which can be relativistic, are given as a function of the shock propagation speed. Then, simulations of shock waves are performed by use of a one-dimensional, relativistic, electromagnetic particle code with full ion and electron dynamics. The shock speeds in the simulations were in the range 0.5 ≤ v sh / c ≤0.9. The simulation results on ion orbits and energies are compared in detail with the theory.