Collimated ion beam by a tailored target illuminated by an intense short pulse laser

In a laser-foil interaction for an ion beam generation, suppression of a transverse proton beam divergence is realized by a tailored thin foil target, which has holes at the rear side of the target. The electron and proton clouds are limited in transverse by the plasma at the protuberant part. In this paper, we investigate the robustness of the hole target for the high quality proton beam generation in the laser-plasma interaction. The transverse edge effects of the ion cloud and the electron cloud deform the potential shape, which defines the proton extraction direction. Consequently the proton beam divergence is induced by the deformed potential shape. The protuberant part of the hole target shields the edge fields of the ion and electron clouds. The present work demonstrate that the hole target is robust against the additional contaminated proton source layers. The multiple-hole target is also robust against the laser alignment error and the target positioning error. The multiple-hole target may serve a robust target to produce a collimated proton beam in realistic experiments and uses