On the Influence of the Gouy Phase on the Process of Direct-Field Electron Acceleration

Direct-field laser acceleration of electrons by radially polarized laser pulses with a tunable total Gouy phase variation (TGPV) is investigated. It is shown, using test-particle simulations, that the Gouy phase plays a fundamental role in the synchronization process between the laser pulse and electrons. Simulations reveal that a smaller TGPV is advantageous and can lead to up to 25% increase in the theoretical energy limit, as well as up to 50% more energy yield, within the limits of the parameter space explored in the present work, as compared to the results predicted for a standard T M 01 pulse. We also examine the possibility of using direct-field laser acceleration in a cascade configuration using pulses with a TGPV smaller than 2 π , pointing out the fundamental limitations of that approach.