Properties of electrons scattered on a strong plane electromagnetic wave with a linear polarization: classical treatment

TL;DR

This paper analyzes how ultrarelativistic electrons scatter on a strong, linearly polarized electromagnetic wave using classical equations with radiation reaction, revealing weak dependence on initial conditions and a universal reflection law.

Contribution

It provides an exact classical treatment of electron scattering on a strong electromagnetic wave, including radiation reaction effects, and derives a universal reflection law for electrons.

Findings

Electrons are mainly scattered at small angles.

Maximum Lorentz factor depends on the work done by the field.

Reflected electrons lose energy but stay relativistic.

Abstract

The relations among the components of the exit momenta of ultrarelativistic electrons scattered on a strong electromagnetic wave of a low (optical) frequency and linear polarization are established using the exact solutions to the equations of motion with radiation reaction included (the Landau-Lifshitz equation). It is found that the momentum components of the electrons traversed the electromagnetic wave depend weakly on the initial values of the momenta. These electrons are mostly scattered at the small angles to the direction of propagation of the electromagnetic wave. The maximum Lorentz factor of the electrons crossed the electromagnetic wave is proportional to the work done by the electromagnetic field and is independent of the initial momenta. The momentum component parallel to the electric field strength vector of the electromagnetic wave is determined only by the diameter of the laser beam measured in the units of the classical electron radius. As for the reflected electrons, they for the most part lose the energy, but remain relativistic. There is a reflection law for these electrons that relates the incident and the reflection angles and is independent of any parameters.