Characterization of laser-driven shocks of high intensity using piezoelectric polymers

Abstract

Piezoelectric elements made of polyvinylidene-fluoride-trifluoroethylene copolymer P͑VDF/TrFE͒ have been used to measure the pressure induced 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 application of such piezoelectric materials under those conditions is new, and a special effort has been made for their improvement and characterization 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 at each shot, using simple assumptions. Next, a more accurate analysis of the data, involving computer simulations, has provided the pressure profiles characterizing the laser shocks driven on the front surface of the targets, over a wide range of laser intensities. Peak pressures of 7-60 GPa on the irradiated surface have been inferred from that analysis. The results have been compared to values obtained from a classical scaling law on one hand, and to predictions of a laser-matter interaction simulation code on the other hand. An overall coherence has been obtained, despite some discrepancies that have been discussed.

Planar shock waves in liquids produced by high-energy KrF laser: A technique for studying hydrodynamic instabilities

“…The relationship for the oscilloscope response is given by de Rességuier et al (1996) and Peyre et al (2000) …”

“…However, the most common technique for shock pressure measurements is piezoelectric gauges. Thin polyvinylidene-fluoride (PVDF) film and its copolymer with trifluoroethylene P(VDF/TrFE) after specific treatments (stretching and subsequent application to electric field) demonstrate strong piezoelectric effect, being the most suitable material to construct different types of pressure gauges (Obara et al, 1995;de Rességuier et al, 1996;Bauer, 2003). The polymer piezoelectric gauges in comparison with more usual X-cut crystalline quartz (Graham, 1975;Fabbro et al, 1990;Devaux et al, 1993) have evident advantages: (1) higher sensitivities, which is important for moderate laser intensities and respectively moderate generated pressures in the presence of a strong parasitic noise; (2) linear response for higher pressure values.…”

“…A specific resin whose acoustic impedance was matched with the copolymer's one filled the transducer body to avoid SW reflection on the rear surface of the copolymer. The calibration test with flyer impacts was carried out earlier that gave for a piezoelectric constant a value K ¼ 5.35 mC/cm 2 (de Rességuier et al, 1996). The transducer current was delivered to Tektronix TDS 2024 scope with 100-V twisted-pare cable loaded by two 100-V resistors in parallel.…”

Experimental determination by PVDF and EMV techniques of shock amplitudes induced by 0.6-3 ns laser pulses in a confined regime with water

“…This technique has already been used to evaluate the shock amplitudes induced by 10-20 ns pulses and some 5-6 GPa maximum levels were evidenced with saturation occurring above 10 GW cm −2 due to breakdown phenomena at the surface of the water [4]. Other techniques can also be used to measure shock amplitudes: we present here some original results obtained by EMV [8] and copolymer [9,10] techniques to characterize laser-driven shock amplitudes † Laboratoire pour l'Utilisation des Lasers Intenses -UMR No 7605 CNRS-CEA-Ecole Polytechnique-Université Paris VI-91128 Palaiseau, France. induced by 0.6 ns and 3 ns pulses as compared with more than 10 ns shocks.…”

Optimización de campos de tensiones residuales en procesos de tratamiento superficial de materiales metálicos mediante ondas de choque generadas por láser

“…ii) Transductores de presión cuarzo [Bushnell68,Fairand76a,Devaux91], piezoeléctricos [Fabbro90,Resseguier96,Resseguier98] o cerámicos [Bushnell68]. En todos los casos se transforma el pulso de presión que alcanza al transductor en una señal eléctrica que permite visualizar temporalmente la magnitud del mismo.…”