Lorentz force on an electron in a strong plane-wave laser field and the low-frequency limit for ionization

Abstract

A motion of a classical free charge in an electromagnetic plane wave can be found exactly in a fully relativistic case. We have found an approximate non-parameter form of the suitable equations of motion. In a linearly polarized wave, in the simplest frame of reference, the charge moves along the well-known "figure-8" path. We have numerically calculated the Lorentz force acting on the charge as a function of time. In virtue of this, for the low frequency ionization (or detachment) rate, we discuss a manifestation of nondipole and relativistic effects.