Multi-peak emission of the fast electron beams along the target surface in ultrashort laser interaction with solid targets

The spatial and energy distributions of fast electrons emitted from foil targets irradiated by ultrashort intense laser pulses are measured. Four groups of collimated emissions of fast electrons along the front and rear target surfaces are observed for an incidence angle of < 60°. This multi-peak characteristic is found to be independent of the polarization states. Numerical simulations reveal that the electron beams are formed due to the deformation of the target surface and then guided by the induced quasistatic electromagnetic fields.