In the present work, we investigate the impact of a thin metallic coating on proton acceleration from transparent dielectric foils. A substantial difference in the experimental results is observed based on the placement of the thin metal coating—either on the front surface (the side facing the laser) or on the rear surface of the foil. In the former case, we observed an enhancement in both the energy and flux of the accelerated protons/ions. However, in the latter case, the thin metal coating was found to have a highly detrimental effect on the acceleration process. Measurements conducted on transmitted laser pulse signals confirm the crucial role of the intensity-dependent target material transparency and the laser pre-pulse playing vital roles in determining the proton/ion acceleration dynamics. Numerical simulations involving radiation hydrodynamics followed by two-dimensional particle-in-cell simulations confirm the experimental observations.
This paper investigates how a thin metal coating on a transparent dielectric foil affects proton acceleration. The results show that the placement of the coating (front or rear) has a significant impact - front coating enhances proton energy and flux, while rear coating is detrimental. This is due to the role of target transparency and laser pre-pulse in the acceleration dynamics.