Ion acceleration boosted by recycling of the reflected laser pulse in target-normal-sheath-acceleration

Abstract

This paper suggests recycling of a reflected laser pulse using a secondary target to boost the maximum ion energy and the beam charge in target normal sheath acceleration (TNSA). In the regular TNSA, energy coupling between the laser pulse and the target is low, as a large fraction of the laser energy is reflected from the target. In our double-target scheme, the secondary target reflects the laser pulse back to the main target, leading to reinforcement of the accelerating sheath field. In two-dimensional particle-in-cell simulations, we observed that the maximum ion energy was enhanced by up to 60 percent and the beam charge was increased by a factor of three compared with the regular single-target system. In addition, the tilted angular distribution of the ion beam for oblique irradiation in TNSA became more symmetric owing to the second irradiation. We found that the maximum ion energy and the beam charge are larger for shorter distances between the targets. We also found that the double-target configuration is effective in boosting the ion acceleration even in the presence of pre-plasmas.