Radiation friction force effects on electron dynamics in ultra-intensity laser pulse

The electron dynamics in the ultra-high intensity laser pulse with radiation friction force in theLandau-Lifshitz form are studied. It is demonstrated that widely used approximation, where onlythe term dominating the dissipation of electron kinetic energy is retained in the expression for theradiation friction, is incorrect for the case of diverging electron trajectories. As a matter of fact, forlarge friction force effects, all components of the radiation friction force in the Landau-Lifshitz formhave the same order in the equation of electron motion, being equally important for both electrontrajectory and thus energy gain in the case of diverging electron trajectories (e.g. determined bythe superposition of few electromagnetic waves).