Application of a semi-Lagrangian scheme in the relativistic regime of laser interaction with an overdense plasma slab

A one-dimensional relativistic semi-Lagrangian Vlasov–Maxwell code is here outlined in an application to the simulation of the interaction of relativistically strong laser pulses with overdense plasmas. Algorithmic differences are briefly recalled with respect to the regimes for which a straightforward time-splitting scheme is applicable. As an example of the accuracy of the semi-Lagrangian scheme, we present some strictly kinetic features of the penetration process of an intense laser pulse inside an overdense plasma by self-induced transparency. In particular we show the formation of vortical trapping structures in the electron distribution function, due to the beat-wave process between the incident laser light and the doppler-shifted reflected wave. These coherent structures are later destroyed due the formation of an electron-cavitation, which develops close to the density peak near the propagating front-wave, thus separating the relativistically underdense and overdense regions.