ÉTUDE EXPÉRIMENTALE DU RALENTISSEMENT DANS LES GAZ DE L'ÉJECTION DE MATIÈRE INDUITE PAR CHOC

We describe an experimental technique using both flash X-Ray radiography and ultra-high speed framing camera shadowgraphy in order to study the slowing down of shock-induced matter ejection appearing when a dense gaz is put ahead the sample free surface. Experiments have been achieved with tin shocked at 40 GPa by an explosive plane wave generator or at 16 GPa by an explosive lateral wave generator and different gas (argon, nitrogen, helium) at different initial pressures (from 0 to 0.8 MPa). With argon gas, we show up a drastic slowing down of the ejected particles and, sometimes, a quick stopping (a few microseconds after shock bursts into the gas), which directly depends on the argon initial pressure. Nitrogen induces a slowing down less strong than argon, and helium has no influence on the ejected particle motion.