Comparative study of radially polarized Gaussian versus Super-Gaussian beam-induced electron acceleration through IFEL-type interaction

Abstract Direct laser acceleration (DLA) of electrons in vacuum is investigated using a radially polarized Gaussian and Super-Gaussian (RP SG) laser beam in the presence of an externally applied wiggler magnetic field. SG beam profiles exhibit a flatter transverse intensity distribution and reduced diffraction compared to conventional Gaussian beams, thereby providing a more uniform accelerating field over an extended interaction region. A normalized relativistic model is employed to examine the influence of the SG order on the longitudinal electric field and the resulting electron energy gain. It is found that increasing the Super-Gaussian order enhances the field uniformity and extends the effective acceleration length up to 12.7 µm, leading to improved energy transfer to electrons. The presence of the wiggler magnetic field induces transverse oscillations that enable sustained phase synchronism with the laser field through an inverse free-electron laser (IFEL)-type interaction, resulting in significant energy enhancement. For a laser wavelength of 800 nm and intensity I ∼ 3.4 × 10 19 W/cm 2 , the maximum electron energy increases from 0.82 GeV for a Gaussian beam ( m = 1) without a wiggler magnetic field to 1.42 GeV in the presence of the wiggler field, and further to 4.15 GeV for an RP SG order ( m = 4) combined with wiggler-assisted acceleration. These results demonstrate the strong synergistic effect of beam shaping and IFEL-based phase synchronization in enhancing vacuum electron acceleration. These results demonstrate that the combined use of Super-Gaussian beam shaping and magnetic modulation provides an efficient and controllable mechanism for vacuum electron acceleration, with potential applications in compact accelerators.