Relativistic electron bunches accelerated by radially polarized TW lasers from near-critical-density plasmas

Abstract

By three-dimensional particle-in-cell simulation, we study electron acceleration by tightly focusing a few-cycle radially polarized laser onto near-critical-density plasmas. Laser ponderomotive force first pushes electrons into the target, forming a compressed electron layer and leaving behind a charge-separation field. Together with the strong longitudinal electric field of this radially polarized light, the charge-separation field accelerates the electrons backward and injects them into laser fields. The reflected light continuously accelerates these injected electrons by its longitudinal field. Simulations show that a tight quasi-monoenergetic electron bunch at 15 MeV is generated within a few micrometers.