Nonlinear electron heating in ultrahigh-intensity-laser–plasma interaction

Abstract

The interaction of an ultraintense laser pulse with an overcritical collisionless plasma at normal incidence is investigated with 1.5 dimensional particle-in-cell simulations. Laser absorption and hot electron energy are reported for a large range of intensities and plasma densities. We observe a strong dependence of the electron temperature on the plasma density profile, and a transition between two different heating mechanisms when the gradient length is varied. For sharp edged profiles, the electron temperature is well below the laser ponderomotive potential.