RELATIVISTIC DRIFT OF AN ELECTRON UNDER THE INFLUENCE OF A SHORT INTENSE LASER-PULSE

In the context of the problem of ionization of an atom by a very stron g laser field, we use the planewave approximation to consider a drift of a classical electron in a light field. The conditions of applicabil ity of the employed approximations are discussed. In particular, the c onditions for neglecting spatial inhomogeneity of the field and electr on drift due to gradient forces are analyzed. We present the solutions to relativistic equations of motion expressed in terms of the integra l of the electric-field strength in the incident wave over the phase. We discuss competition, similarity, and distinguishing features of the electron drift along the direction of the electric-field vector (drif t due to initial conditions) and along the direction of wave propagati on (drift due to the Lorentz force). The applicability of the adiabati c approximation for the analytical calculation of the integrals that d etermine solutions is analyzed.