Master 2 internship – Von Neumann reflection in solid evidenced using laser-generated shock

Due to their intrinsic non-linearity, shock waves may display unique features. In particular, in case of an oblique reflection on a rigid interface, Snell-Descartes laws are no more satisfied by the wave. Depending on the incidence angle and shock amplitude, incident and reflected angles are different and reflected shocks can merge away from the reflection surface, at a particular position called the triple point, connected to the reflecting surface by a third wave called Mach stem. Behavior of the Mach stem itself depends of the strength of the incident shock wave. In our studies, we are particularly interested by the case of a weak shock wave for which the ratio of medium velocity to wave velocity is small but finite. For such waves, the Mach stem wavefront is curved, this particular regime being called « von Neumann reflection ». Such typical behavior has been extensively observed and investigated in air, with a few observations in water. However, in case of solids, it is only hypothesized that such nonlinear reflection of a weak shock wave occurs. The objective of the internship is to demonstrate this for the first time in solids

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