High-quality proton bunch from laser interaction with a gas-filled cone target

摘要

Generation of high-energy proton bunch from interaction of an intense shortcircularly polarized(CP) laser pulse with a gas-filled cone target(GCT) isinvestigated using two-dimensional particle-in-cell simulation. The GCT targetconsists of a hollow cone filled with near-critical gas-plasma and a thin foilattached to the tip of the cone. It is observed that as the laser pulsepropagates in the gas-plasma, the nonlinear focusing will result in anenhancement of the laser pulse intensity. It is shown that a large number ofenergetic electrons are generated from the gas-plasma and accelerated by theself-focused laser pulse. The energetic electrons then transports through thefoil, forming a backside sheath field which is stronger than that produced by asimple planar target. A quasi-monoenergetic proton beam with maximum energy of181 MeV is produced from this GCT target irradiated by a CP laser pulse at anintensity of $2.6\times10^{20}W/cm^2$, which is nearly three times highercompared to simple planar target(67MeV).