Relativistic Ponderomotive Force Including Higher Order Nonlocal Effects in High Intensity Laser Fields

Abstract

Based on the noncanonical Lie perturbation theory, we derived a new formula for relativistic ponderomotive force in a transversely localized laser field, which is accessible to the regime where the conventional formula described in terms of the local field gradient can hardly be applied. The formula involves new terms represented by second and third spatial derivatives; therefore, the force depends not only on the local field gradient, but also on the curvature and its variation. A physical explanation for these terms is given.