Laser-driven electron acceleration in nanoplate array targets.

Abstract

This paper proposes a model of the laser-driven electron acceleration that occurs when a high-intensity laser interacts with a nanoplate target. It shows that quasistatic electric E_{qs} and magnetic B_{qs} fields can be formed when the laser, polarized normal to the nanoplates, extracts electrons from the nanoplates. Considering the physical natures of E_{qs} and B_{qs}, the amplitude of E_{qs} is relatively larger than B_{qs}. Such a residual between static electric and magnetic field is shown to be crucial for the electron acceleration beyond the ponderomotive scaling, as it can cause onset of stochastic electron motion. The analysis demonstrates that the maximum electron energy in units of ponderomotive scaling depends on a single universal parameter, which is composed of laser amplitude, spacing between nanoplates, and electron initial conditions. The analytical results are confirmed by a series of two-dimensional particle-in-cell simulations using epoch code.