Focusing of laser-accelerated proton beams using curved targets, and improved energy deposition

We use numerical simulations for laser-plasma interaction and particle transport, to study proton acceleration from curved targets and their potential for isochoric heating. Combining a proton dot geometry, to produce a low-energy cut-off in the accelerated proton beam spectrum, and a cylindral shape of the substrate, to bend proton trajectories, we compute increased energy deposition in an auxiliary target placed in the proton beam path, compared to protons that would be accelerated from a flat substrate. The highest temperatures are obtained when placing the auxiliary target slightly after the theoretical focus position, confirming the trend observed in the PIC simulations that cylinders focus slightly after their radius. Moving the target out of the proton beam focus, the peak temperature decreases and a larger transverse region can be heated.