Hot electron generation via vacuum heating process in femtosecond laser–solid interactions

Hot electron generation by the vacuum heating process has been studied in the interaction of 150 fs, 5 mJ, 800 nm P-polarized laser pulses with solid targets. The measurements have suggested that the “vacuum heating” is the main heating process for the hot electrons with high energies. The energy of the vacuum-heated hot electrons has been found to be higher than the prediction from the scaling law of resonance absorption. Particle-in-cell simulations have confirmed that the hot electrons are mainly generated by the vacuum heating process under certain experimental conditions.