Influence of beam profile on the pressure generated by light ion beams

Simulations are performed for the ablation pressure generated by proton beam at KALIF. It is seen that the scaling of ablation pressure to the 2/3 power of beam flux is valid only at high beam power. At low beam power the temporal profile of the beam plays an important role in determining the peak pressure generated at the target. If the peak beam energy is reached before the peak power, it is this peak beam energy that determines the time at which the peak pressure is reached. Due to the range shortening effect (supplemented by the decrease in beam energy) energy is deposited in the ablating plasma and is not available for pushing the target. At high beam power, however, the ablation zone is heated to temperatures high enough to cause range lengthening and the scaling of the ablation pressure with the beam flux to the power of approximately 2/3 is valid.