Claire Michaut

Radiative shocks: An opportunity to study laboratory astrophysics

In this paper, experimental results on radiative shocks generated by a high power laser in a xenon gas cell are presented. Two sets of experiments have been performed at the Laser pour lUtilisation des Lasers Intenses (LULI) laboratory. Several shock parameters were simultaneously measured: shock temperature and velocities, the precursor two-dimensional (2D) time evolution, its electron density, density gradient, and temperature. Data were obtained varying initial conditions for different laser intensities and gas pressures. Comparisons with 1D and 2D radiative hydrodynamic simulations are shown for all measured parameters (shock velocity, shape, radial expansion, and temperature as well as precursor velocity and electron density).

Temperature and electron density measurements on laser driven radiative shocks

In this paper, new results on radiative shocks generated by a high power laser in a xenon gas cell are presented. Several shock parameters were measured: temperature, radial expansion and velocity, as well as the electron density in the radiative precursor and its velocity. Multiple laser shot allowed the investigation of physical trends changing initial conditions (laser energy and initial gas pressure). Results are compared with one- and two-dimensional radiative hydrodynamic simulations. The experiments were carried out at the LULI Laboratory.

Modeling multidimensional effects in the propagation of radiative shocks

Radiative shocks (also called supercritical shocks) are high Mach number shock waves that photoionize the medium ahead of the shock front and give rise to a radiative precursor. They are generated in the laboratory using high-energy or high-power lasers and are frequently present in a wide range of astronomical objects. Their modelization in one dimension has been the subject of numerous studies, but generalization to three dimensions is not straightforward. We calculate analytically the absorption of radiation in a gray uniform cylinder and show how it decreases with χR, the product of the opacity χ and of the cylinder radius R. Simple formulas, whose validity range increases when χR diminishes, are derived for the radiation field on the axis of symmetry. Numerical calculations in three dimensions of the radiative energy density, flux, and pressure created by a stationary shock wave show how the radiation decreases with R. Finally, the bidimensional structures of both the precursor and the radiation fiel...