The generation of laser shock waves in a water-confinement regime with 50 ns and 150 ns XeCl excimer laser pulses

The generation of shock waves by laser-induced plasma in a water confinemen t regime has been investigated with 0.308 mu m/50 ns and 0.308 mu m/150 ns excimer laser pulses. Shock-wave profiles have been characterized by numeri cal simulations of rear surface velocity measurements behind Al foils with the use of a velocity interferometer system. The results are compared with those obtained with the third harmonic of a Nd:Yag. Above 1-2 GW cm(-2), pr essure levels saturate at 2-2.5 GPa and the pressure duration is much short ened by laser plasma breakdown which occurs in water. Therefore we suggest that this parasistic plasma generation is favoured by long pulse durations and a laser with short wavelengths.