Compressive shock directly driven by ultra-intense laser

The plasma compression and shock generation along the light pressure gradient were investigated in an ultra-intense laser irradiated plasma, where the light pressure was dominated over the thermal one. The threshold for directly driven shock and scaling laws for hydrodynamic parameters were calculated by the piston model. The dependence of the propagation speeds of the shock and the critical fronts on the ratio between the oscillation and the thermal energies of the free electron in the light field shows that the spatial dimension of the compressed plasma between these two fronts are increased during propagation towards target.