Hybrid simulation of shock-bubble interaction in multi-species plasmas

The shock-bubble interaction in multi-species plasmas has been investigated via the hybrid fluid-particle-in-cell (PIC) method. Compared with the passive and active scalars used in hydrodynamic simulations, the shock-induced multi-ionic interpenetration is captured by first-principles PIC treatment of multi-species ions, which reveals a dual mixing mechanism involving both ion kinetic effects and plasma diffusion. The results show a mixed area about 2 times the initial bubble, causing a transformation from a nearly “chunk mixing” state to approaching an “atomic scale mixing” state. The momentum transport property is significantly changed in the mixed plasmas, showing an increase of the plasma viscosity that is involved self-consistently via the multi-ionic collisions. Shock-induced vortices are found to be dissipated persistently by the mixing-increased viscosity, indicating a decrease of the Reynolds number. Present results provide a better understanding of the mixing feature and hydrodynamic evolution during the shock propagation in inhomogeneous medium in ICF implosions.