Stochastic electron heating in the laser and quasi-static electric and magnetic fields

TL;DR

This paper investigates how relativistic electrons gain energy through stochastic processes in intense laser and quasi-static electromagnetic fields, revealing limits on electron energy and effects of field parameters through analytical and numerical methods.

Contribution

It introduces a Hamiltonian framework to analyze stochastic electron heating in combined laser and static fields, deriving criteria for instability and energy limits.

Findings

Maximum stochastic electron energies depend on laser intensity and electric field strength.

Strong laser intensity enhances stochastic energy, while weak electric fields do the same.

Superluminal phase velocity reduces stochastic heating effects.

Abstract

The dynamics of relativistic electrons in the intense laser radiation and quasi-static electromagnetic fields both along and across to the laser propagating direction are studied in the 3/2 dimensional Hamiltonian framework. It is shown that the unperturbed oscillations of the relativistic electron in these electric fields could exhibit a long tail of harmonics which makes an onset of stochastic electron motion be a primary candidate for electron heating. The Poincar\'e mappings describing the electron motions in the laser and electric fields only are derived from which the criterions for instability are obtained. It follows that for both transverse and longitudinal electric fields, there exist upper limits of the stochastic electron energy depending on the laser intensity and electric field strength. Specifically, these maximum stochastic energies are enhanced by a strong laser intensity but weak electric field. Such stochastic heating would be reduced by the superluminal phase velocity in both cases. The impacts of the magnetic fields on the electron dynamics are different for these two cases and discussed qualitatively. These analytic results are confirmed by the numerical simulations of solving the 3/2D Hamiltonian equations directly.