Ablative Radiative Shock Experiments C. Michaut 1 , M. Koenig 2 , P. Barroso 3 , L. Van Box Som 4 , E. Falize 4 , Y. Sakawa 5 , T. Sano 5 , Y. Hara 5 , H. Shimogawara 5 , R. Kumar 5 , T. Morita 6 , T. Miura 6 , S. Shiiba 6 , N. Katsuki 6 , S. Tomiya 7 , B. Albertazzi 8 , T. Ogawa 8 , Y. Fujimoto 8 , Y. Matsumura 8 , T. Nisikawa 8 , K. Tanaka 8 , R. Hazama 8 1 LUTH, Observatoire de Paris, PSL Research University, CNRS, Université Paris Diderot, Sorbonne Paris Cité, 92190 Meudon, France 2 LULI - CNRS, Ecole Polytechnique, CEA : Université Paris-Saclay ; UPMC Univ Paris 06 : Sorbonne Universités - F-91128 Palaiseau, France 3 GEPI, Observatoire de Paris, PSL Research University, CNRS, Université Paris Diderot, Sorbonne Paris Cité, 75014 Paris, France 4 CEA, DAM, DIF, F-91297 Arpajon, France 5 Institute of Laser Engineering, Osaka University, Suita 565-0871, Japan 6 Department of Energy Engineering Science, Faculty of Engineering Sciences, Kyushu University, Japan 7 Aoyama Gakuin University, Shibuya-ku, Tokyo, Japan 8 Graduate School of Engineering, Osaka University, Suita, Osaka 565-0871, Japan INTRODUCTION In astrophysics, the dynamics of interstellar medium is closely linked to the interaction between radiative structures (radiative shock, Marshak wave) and inhomogeneous/clumpy media. One of the most beautiful examples is the Eagle Nebula in M16, otherwise referred to as the Pillars of Creation. This spectacular phenomenon is commonly seen wherever molecular clouds around massive stars (O and B stars). Such hot stars produce intense UV radiation bathing the surface of nearby molecular clouds, causing ablation or photo-evaporation. The absorbing layers become hot and vaporize, in response to which a strong-shock compression wave is launched into the cloud. Dense evaporating gaseous globules will evolve in stellar nurseries. Proposed formation mechanisms for such pillars usually involve instabilities at the boundary between the cloud and the ionized region, which grow with time [1-4]. Many other phenomenon involving strong radiative shocks (RS) disturb and inject energy into the interstellar medium, affecting the rate of star formation in galaxies. They are referred to as “feedback mechanisms,” and studying them is critical to understanding galaxy evolution. Therefore, the interaction of strong radiative shock waves with other structures is a central problem in astrophysics, just as it is in inertial-confinement fusion (ICF) where spherical RS have been recently observed in cryogenic implosions [5]. In this new experiment regarding RS, we aimed to observe the interaction of the radiative precursor with a solid object as a mock-up of the ablation processes in molecular clouds or similar objects. To achieve this, we have generated on the GEKKO XII facility, a strong radiative shock in a dedicated gas-cell that lies in the so-called radiative precursor regime, i.e., where Bo < 1 and R >1. We used the long generated precursor to observe its interaction with a solid foil. Optical diagnostics were carefully set up in order to measure all possible parameters related to strong RS. We clearly observed a set in motion of this foil due to absorption of the radiation emitted by the strong RS. From the measured expansion velocity, we inferred the associated temperature that is 1-2 eV. EXPERIMENTAL SET-UP In order to study the interaction between a radiation flux and a surface, we used our traditional gas-cell targets specifically built with an obstacle put few millimeters after the radiative shock breaks out the pusher (Fig. 2). This year we have changed how the balloon is