Multiple shocks near Mars

Mars presents us with an example of a magnetosheath in which the interaction of the solar wind with planetary plasma of heavy ions results in a generation of strong nonlinear bi-ion MHD waves. These waves provide oscillations in the momentum exchange between protons and heavy ions and may give rise to multiple shock-like structures. One-dimensional hybrid simulations of plasma flow interaction with a "heavy ion obstacle" were performed to study the generation of shock waves in bi-ion plasma. A differential motion of protons and heavy ions leads to bunching of heavy ion flow picked up by solar wind. Plasma bunching arises because of a resonant interaction between magnetosound waves excited by beam and "slow" waves of a spatial charge in the heavy ion flow. Both kinds of waves grow, steepen and gradually evolve to shocks.