Role of laser pulse asymmetry in electron acceleration in vacuum in the presence of an axial magnetic field

Abstract

The role played by temporal asymmetry in a linearly polarized laser pulse on the acceleration of an electron in vacuum in the presence of an axial magnetic field has been investigated. The temporal shapes of the laser pulses considered here are Gaussian, positive skew (sharp rise and slow fall), and negative skew (slow rise and sharp fall). Since the pulse amplitude rises sharply in the case of positive skew, the electron experiences a strong intensity gradient during its interaction with the laser pulse, which strengthens the ponderomotive force. On the other hand, the electron experiences a gradual rise in pulse amplitude for a longer time duration in the case of negative skew. The electron energy is observed to be highest for a pulse with negative skew at low laser intensities and for a pulse with positive skew at high laser intensities. In the presence of an axial magnetic field, electron energy is observed to be highest for a pulse with positive skew at both low and high laser intensities.