Lateral hot electron transport and ion acceleration in femtosecond laser pulse interaction with thin foils

Abstract

Hot electron transport along the target surface out of the laser-irradiated spot plays an important role in such applications as ion acceleration or fast ignition of fusion reactions. In this paper, the lateral electron transport in a thin foil, limited in transverse sizes, is studied by numerical particle-in-cell simulations for two linear polarizations (p and s) of femtosecond laser pulse incident on a foil at various angles. Two mechanisms of the transport are identified: the first one is due to hot electron recirculation across the foil and the second is electron guiding along the foil surface by quasistatic magnetic and electric fields. It is demonstrated that the second mechanism takes place for larger incidence angles, although the recirculation is still important. The ions accelerated from a lateral foil edge, which is out of the laser focal spot, can have higher energies than the ions from the rear foil side.