The interaction and interpenetration of two counter-propagating plasma shocks are investigated via hybrid fluid particle-in-cell simulations. This study seeks to probe the kinetic effects and ion collisions on the structure of colliding plasma shocks in complex multi-ion-species plasma, in particular, the presence of the expansion of high-Z plasma bubbles against the low-Z filled gas inside an ICF hohlraum. The plasma shock waves which are generated at the interface of the high-Z and low-Z plasma, propagate into the filled gas and converge on the axis. The interaction of two shock waves inside the low-Z and low-density plasma, which are dominated by the kinetic effects, is mainly a pass-through process. The shock wave structure and electromagnetic field pass through each other. The superposition of shock wave results in a wave-like electric field in the downstream region. The electric field can further reduce the kinetic energy of the incoming particles, and modulate the ion density profile. It finally generates a new downstream platform of high temperature and high density. However, on the hundred-ps time scale, cumulative ion collisions can still significantly alter the structure of the shock wave and the reflection of ions by the shock front. This study will help to improve the predictions of hohlraum plasma states and the understanding of the shock wave interactions.
 

multi-ion-species plasma,shock wave interaction,ion kinetic effects,ion collisions