CHARACTERIZATION OF LASER-DRIVEN SHOCKS OF HIGH-INTENSITY USING PIEZOELECTRIC POLYMERS

Piezoelectric elements made of polyvinylidene-fluoride-trifluoroethyle ne copolymer P(VDF/TrFE) have been used to measure the pressure induce d on the rear surface of metallic foils irradiated by infra-red laser pulses of 1.5 ns duration, with intensities up to 3 TW/cm(2). The appl ication of such piezoelectric materials under those conditions is new, and a special effort has been made for their improvement and characte rization under plate impact loading, Then, the laser experiments have been carried out. First, peak pressures of 0.5-7.5 GPa transmitted in the copolymer have been derived from the peak voltage measured al each hot, using simple assumptions. Next, a more accurate analysis of the data, involving computer simulations, has provided the pressure profil es characterizing the laser shocks driven on the front surface of the targets, over a wide range of laser intensities. Peak pressures of 7-6 0 GPa on the irradiated surface have been inferred from that analysis. The results have been compared to values obtained from a classical sc aling law on one hand, and lo predictions of a laser-matter interactio n simulation code on the other hand. An overall coherence has been obt ained, despite some discrepancies that have been discussed. (C) 1996 A merican Institute of Physics.