Ion acceleration by colliding electrostatic shock waves in laser-solid interaction

Based on particle-in-cell simulations, ion acceleration by collisionless electrostatic shock waves in the interaction of intense laser pulses with solid targets containing two ion species of different charge-to-mass ratios R is studied. The acceleration processes of the ions with different R and located in different regions of the target have been considered. Simulations also show that ions with larger R can be reflected and accelerated dramatically between two oppositely propagating shocks generated in plasma dominated by ions with smaller R. The studies suggest a new way to generate high energy ions. The involved phenomena may also occur in space and astrophysical plasmas.