Efficient Generation of High-Quality Proton Beam in Laser Tailored-Target Interaction*

Improvement of energy conversion efficiency from laser to proton beam is demonstrated in a laser-foil interaction. When an intense short-pulse laser illuminates the thin foil target, the foil electrons are accelerated around the target. The hot electrons generate a strong electric field, which accelerates the foil protons, and the proton beam is generated. In this paper a multihole thin-foil target is proposed in order to increase the energy conversion efficiency from laser to protons. The multiholes transpiercing the foil target help to enhance the laser-proton energy conversion efficiency significantly. 2.5-dimensional particle-in-cell simulations present that the total laser-proton energy conversion efficiency becomes 9.3{\%} for the multihole target, though the energy conversion efficiency is 1.5{\%} for a plain thin foil target. The transpiercing multihole target serves a new method to increase the energy conversion efficiency from laser to ions. \\[4pt] [1]~R. Sonobe, et al., Phys. Plasmas, 12 (2005) 073104. \\[0pt] [2] Y. Nodera, et al., Phys. Rev. E78 (2008) 046401.