Stochastic electron acceleration in relativistic laser pulse and stationary periodic electric and magnetic fields

Abstract

The mechanisms of stochastic electron acceleration in relativistic laser pulses and stationary periodic electric and magnetic fields are investigated by employing a new Hamiltonian approach. The new Hamiltonian is the dephasing rate between the electron and laser pulse such that it is time independent when the stationary fields are absent. The physics underlying stochastic electron motion is clearly revealed, and the conditions for triggering stochastic instability are obtained by finding the Chirikov-like mapping. It demonstrates that if the amplitudes of the stationary fields exceed some threshold values, the Hamiltonian can be randomly changed, and thus, net energy transfer between electrons and the laser radiation are possible. The maximum electron energy gained from the stochastic motion has a weak dependence on the amplitude of stationary fields and can significantly exceed the vacuum ponderomotive energy. All these analytical results have been confirmed by the numerical simulations.