Studies of interactions of femtosecond laser pulses with foil targets

The emission of hot electrons is measured in the interaction of femtosecond laser pulses with foil targets at a moderate laser intensity. A collimated jet of backward hot electrons is observed in the target's normal direction whereas forward hot electrons are found to be deflected to the laser propagation direction. The low energy electrons spread into a much wider cone angle due to the collisional effects in the plasma and the target material. These results are supported by 3D Monte Carlo simulations. The temperature dependence of the hot electrons and laser absorption measurements imply the resonance absorption is partly responsible for the generation of hot electrons.