Laser intensity effects on forward hot electrons in interaction with Al foil

The characteristics of the forward hot electrons produced by 20 TW p-polarized picosecond laser-plasma interactions are studied at laser intensities from subrelativistic to relativistic. The spatial distribution of forward hot electrons is multi-peak distribution, as laser intensity is under 107 W/cm2. When laser intensity is between 1017 and 1018 W/cm2, the peak of the hot electron beam is along the target normal direction. The peak of the hot electron beam shifts to the laser propagation direction from the target normal direction as the laser intensity reaches the relativistic. The temperature of hot electrons fit resonance absorption scaling law as the laser intensity under the relativistic. The temperature of hot electrons is much higher than that expected by the empirical scaling law