Characterization of accelerated electrons generated in foams under the action of petawatt lasers

Abstract

Analytical prediction of accelerated electrons yield from near-critical targets under the action of petawatt laser radiation is complicated with various processes, such as self-focusing and density channel bending. We investigate the properties of accelerated electron beams at fixed parameters of the petawatt laser radiation and the varied target density using three-dimensional "particle-in-cell" simulations. Shown the most advantageous electron acceleration takes place in the density range from 0.5 to 1.0 of the critical density. The use of a smaller laser spot size of 4.25 μm instead of 25 μm makes it possible to obtain 30 times more intense electron beams with energies higher than 50 MeV at the same energy of the laser pulse.