Direct electron bunch acceleration by Laguerre–Gauss laser pulse

Acceleration of a rest electron bunch in vacuum by a Laguerre–Gauss (LG) laser pulse is studied using three-dimensional test-particle simulations. It is found that the ponderomotive force and the phase synchronization process, with the help of each other, cause rest electrons to reach high energies in the laser interaction. The ponderomotive force due to the spatial distribution of a high-intensity LG laser pulse pushes electrons from the rest and accelerates them at first. Then, the accelerated electrons are trapped in the pulse and continue to gain more energy through the phase synchronization process. Unlike the interaction with a Gaussian laser pulse in which to maintain the beam quality was not possible without the intervention of an external factor, using the LG laser pulse reveals the feasibility of generating a GeV high-quality electron bunch with low spread in energy and radial deflection, without applying any external agent.