Plasma edge effect on wake field induced by a short laser pulse

The excitation of a wake electron plasma wave (EPW) by a short laser pulse impinging an underdense homogeneous plasma wall is studied through a one-dimensional analysis. The plasma edge splits the electrons into two sets: a first one that remains located in the plasma and supports the EPW, a second one closer to the plasma/vacuum interface which is pulled out into the vacuum and then returns into the plasma. For laser irradiances exceeding 1018W/cm2, the latter can be trapped in the EPW potential and induce damping of the EPW. Particle simulations illustrate this phenomenon where multi-MeV energy electrons are accelerated in short-length plasmas. (orig.)