PLAS@PAR is pleased to announce the thesis defense of Raj Laxmi Singh (LPP/Lerma) on March 2, 2017 at UPMC (24-34 - 5th floor, room 509) at 10am.

Raj started her PhD in November 2013 with Jean Larour (LPP) and Chantal Stehlé (LERMA).

Title: Strong radiative shocks relevant for stellar environments: experimental study and numerical approach

Strong shocks are present in various astrophysical phenomena. Such shocks are strongly influenced by the radiation through its coupling with hydrodynamics. Thus their topology and dynamics are quite complex. Generating such hypersonic shocks in the laboratory, with controlled conditions, is thus an adequate tool to study the influence of radiation and to compare them with numerical simulations. Such shocks can be generated by intense lasers and electromagnetic devices. The first part of this dissertation concerns the numerical and experimental study of the interaction of two counter propagating laser-driven shocks. The experiments, performed at the kJ PALS laser facility allowed to generate shocks with different speeds (~ 30-55 km/s and 10-25 km/s), in noble gases and low pressure (less than 1 bar). Several diagnostics were implemented: visible interferometry, time- and space-resolved visible spectroscopy, and time integrated XUV spectroscopy. Our experiment shows a strong interaction of one radiative precursor onto the second one. The physical parameters of the plasma were deduced from the diagnostics and compared with 1-D simulation results. The second part is devoted to the design of an experiment where the shock is generated electromagnetically. The optimization of this generator is presented and also the full experimental set up which allows studying shock ~ 30 km/s in noble gas at ~ 1 mbar.