Observation of Laser Driven Supercritical Radiative Shock Precursors

Abstract

We present a supercritical radiative shock experiment performed with the LULI nanosecond laser facility. Using targets filled with xenon gas at low pressure, the propagation of a strong shock with a radiative precursor is evidenced. The main measured shock quantities (electronic density and propagation velocity) are shown to be in good agreement with theory and numerical simulations.

2D numerical study of the radiation influence on shock structure relevant to laboratory astrophysics

“…Until now, radiative shocks have been studied by 1D geometry models, multi-D models with hydrostatic flows, or by adopting the flux-limited diffusion approximation (Bouquet et al 2004;Drake 2007, and reference therein). On the one hand, the multi-D effects (such as lateral losses) can determine the structure of the flow, and on the other hand, at the foot of the radiative precursor, the reduced flux (ratio of the radiative flux to the product of the radiative energy and the light speed) is nearly one so that we are in the transport limit.…”

“…Studies of the dynamics of the precursor of xenon radiative shocks by interferometry (Bouquet et al 2004), and shadowgraphy (González et al 2006b), and of its topology by instantaneous X-ray imaging (Vinci et al 2006) indicate that multi-dimensional effects can affect the shock wave, and, in particular, its precursor. This was attributed to the lateral radiation losses (through the walls of the shock tube), which reduce the amount of radiation heating the precursor and thus affect its structure (Leygnac et al 2006;González et al 2006b).…”

“…The study of radiative shocks on Earth thus require different gases and physical conditions, which can be recreated by high energy installations such as laser or pulsed electric installations (Remington et al 2006). Radiative shock experiments have been performed with high power lasers (Bozier et al 1986(Bozier et al , 2000Keiter et al 2002;Reighard et al 2006;Bouquet et al 2004;González et al 2006b;Busquet et al 2006Busquet et al , 2007. Typically, a 200 J laser in about 1 ns can launch a shock at about 60 km s −1 in targets of millimeter size (Bouquet et al 2004) filled with xenon at pressures of some fractions of bars, whereas supercritical shocks at 100 km s −1 in SiO 2 aerogel, argon, and xenon have been produced at the OMEGA laser (5 kJ).…”

“…Radiative shock experiments have been performed with high power lasers (Bozier et al 1986(Bozier et al , 2000Keiter et al 2002;Reighard et al 2006;Bouquet et al 2004;González et al 2006b;Busquet et al 2006Busquet et al , 2007. Typically, a 200 J laser in about 1 ns can launch a shock at about 60 km s −1 in targets of millimeter size (Bouquet et al 2004) filled with xenon at pressures of some fractions of bars, whereas supercritical shocks at 100 km s −1 in SiO 2 aerogel, argon, and xenon have been produced at the OMEGA laser (5 kJ). Strong shocks have also been generated by a compact pulse-power device (Kondo et al 2006), producing shocks at 45 km s −1 in xenon with different gas pressures of up to 10 −2 bars.…”

Perspectives on high-energy-density physics

“…They have observed structure in radiative blast waves [24][25][26] in Xe gas at ϳ10 km/ s and ϳ10 −5 g / cm 3 . They have diagnosed in detail the radiative precursor ahead of such shocks in Xe gas [27][28][29][30][31] at ϳ50 km/ s and ϳ10 −3 g / cm 3 or in SiO 2 foams. 32 They have diagnosed the structure and dynamics of the shocked material [33][34][35][36][37][38] in Xe gas at ϳ150 km/ s and ϳ10 −2 g / cm 3 .…”