ON THE EXISTENCE OF SHOCK INSTABILITIES AT HUGONIOT PRESSURES BEYOND THE MINIMUM VOLUME

Flow instabilities are among the main issues of ICF studies. Heterogeneities and defects of the material or the geometry are generally considered among the sources of instabilities which are strongly amplified in spherical geometries. According to the theory of D'yakov, some ranges of the Equation of State (EOS) also generate or amplify instabilities in shock waves, which can be considered among the origin of Richtmyer-Meshkov instabilities. It is well known that, on the Hugoniot curve of most materials, the volume decreases versus pressure down to a minimum and then increases with ionization towards an asymptotic value. Recent results in this range of pressure allow us to investigate now the stability conditions. The first question to raise is the possibility of existence of such instabilities. We focus here on the properties of several elements (aluminium, iron, copper) in this range of pressure to try to give a first answer to this question.