Experimental study of proton emission from 60-fs, 200-mJ high-repetition-rate tabletop-laser pulses interacting with solid targets

Measurements of proton emission have been made from a variety of solid targets irradiated by a 60-fs, 200-mJ, $7\times {10}^{18}-{\mathrm{W}\mathrm{}\mathrm{cm}}^{-2}$ laser system operating at 2 Hz. Optimum target conditions were found in terms of target material and thickness. For Mylar targets of thickness 20–40 μm, a maximum proton energy of 1.5 MeV was measured. For aluminum targets, a maximum energy of 950 keV was measured for 12 μm, and for copper, 850 keV for 12.5 μm.