Directional transport of fast electrons at the front target surface irradiated by intense femtosecond laser pulses with preformed plasma

The effects of laser incidence angle on lateral fast electron transport at front target surface, when a plasma is preformed, irradiated by intense (>10 ¹⁸ W/cm ²) laser pulses, are studied by K _α imaging technique and electron spectrometer. A horizontally asymmetric K _α halo, resulting from directional lateral electron transport and energy deposition, is observed for a large incidence angle (70°). Moreover, a group of MeV high energy electrons is emitted along target surface. It is believed that the deformed preplasma and the asymmetrical distribution of self-generated magnetic field, at large incidence angle, play an important role in the directional lateral electron transport.