Experimental study for angular distribution of the hot electrons generated by femtosecond laser interaction with solid targets

Abstract

The experimental results of angular distribution of hot electrons in the interaction of a 60 fs, 125 mJ, 800 nm, ${\text{∼10}}^{17}\hspace{0.17em}{\mathrm{W cm}}^{\text{−2}}$ laser pulse with Al targets are reported. Three obvious peaks of hot electrons emission have been observed, as there is a weak normal component of the laser electric field. These emission peaks are located in the directions of the specular reflection of the laser, the target normal, and the backreflection of the laser, respectively. In the case of the $P$ -polarized laser pulse, which has a strong normal component of the laser electric field, the peak in the backreflection of the laser disappeared, and only two obvious peaks of hot electron emissions existed. It shows that the different directions of hot electrons emission are dominated by different absorption or acceleration mechanisms. The experimental result of the hot electrons energy spectrum at the target normal shows that the effective temperature of hot electrons is about 190 keV, which is consistent with a scaling law of the resonance absorption.