It was shown that in the interactions of ultra-intense circularly polarized laser pulse with the near-critical plasmas, the angular momentum can be transferred efficiently from the laser beam to electrons through the resonance acceleration process. The transferred angular momentum increases almost linearly with the acceleration time t(alpha) when the electrons are resonantly accelerated by the laser field. In addition, it is shown analytically that the averaged angular momentum of electrons is proportional to the laser amplitude alpha(L), and the total angular momentum of the accelerated electron beam is proportional to the square of the laser amplitude alpha(2)(L) for a fixed parameter of n(e)/n(c)alpha(L). These results are verified by three-dimensional particle-in-cell simulations. This regime provides an efficient and compact alternative for the production of high angular momentum electron beams, which may have many potential applications in condensed-matter spectroscopy, new electron microscopes, and bright x-ray vortex generation.

ACCELERATION; GENERATION; DRIVEN

Institute of Applied Physics and Computational Mathematics; Peking University; Shenzhen University