MULTIPLE SHOCKS NEAR MARS

Mars presents us with an example of a magnetosheath in which the inter action of the solar wind with planetary plasma of heavy ions results i n a generation of strong nonlinear bi-ion MHD waves. These waves provi de oscillations in the momentum exchange between protons and heavy ion s and may give rise to multiple shock-like structures. One-dimensional hybrid simulations of plasma flow interaction with a ''heavy ion obst acle'' were performed to study the generation of shock waves in bi-ion plasma. A differential motion of protons and heavy ions leads to bunc hing 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.