High-brilliance gamma bursts by PW-class laser pulses interact- ing with a nanoblade targetompton Scattering in Structured Targets Using 3D PIC Simulations

Gamma radiation sources resulting from laser-plasma interactions take advantage of their small source size and ultrashort duration, therefore resulting in high brilliance. Different configurations based on laser-driven electron acceleration have been proposed in order to enhance laser-target energy coupling and obtain high energy and high photon flux sources, some of them involving structured targets. The setup presented here is inspired by the “peeler” scheme, originally suggested for the generation of monochromatic ion bunches. It consists of an intense laser pulse irradiating the narrow (submicron) side of a solid blade target, with length on the order of a few dozen microns, at normal incidence.

This scheme has been shown to work well for 100TW-class lasers, where the target tip re- mains reasonably intact and most of the photon generation is a result of electrons oscillating as they propagate along the target surface. By using 3D simulations performed with the fully relativistic particle-in-cell code SMILEI, we show that, at higher laser powers, a significant part of the photon generation events occur close to the target tip, where the plasma is pinched and electrons undergo accelerated motion in the laser electric field, thus emitting a large number of synchrotron photons. The resulting brilliance of this source exceeds 1023 second−1 mm−2 mrad−2 0.1% BW−1 at 10 MeV.