Effect of the reflected ions on the magnetic overshoot of a collisionless shock

A collisionless shock transfer of mass, momentum, and energy occurs from upstream to downstream. Most of the momentum and energy fluxes are carried by ions so the shock structure is affected mainly by ions. With the increase in the Mach number, the fraction of reflected ions increases and their influence on the shock structure becomes progressively more important. Here, we study the effect of the reflected ions on the overshoot strength. It is shown that directly transmitted ions are responsible for the overshoot formation and the interaction of the overshoot field with these ions alone might result in an unstable growth of the overshoot. On the contrary, reflected ions, at their second crossing of the shock, are accelerated along the shock normal and, thus, provide a stabilizing effect on the overshoot.