Suppression of high-energy proton beam divergence in laser–foil interaction

A suppression of transverse proton divergence by a localization of high-energy electron bunch generated by an interaction between an intense laser and a foil target is investigated in this paper. When an intense laser illuminates a foil target, electrons are accelerated longitudinally by the ponderomotive force and produce a strong magnetic field. The electrons are confined by the magnetic field and an electric field is generated locally. Protons are extracted and mainly accelerated longitudinally by the local electric field. Consequently, the transverse divergence of high-energy protons is successfully suppressed.