Progress in the study of warm dense matter

In the last few years, high power lasers have demonstrated the possibility to explore new state of matter the so-called Warm Dense Matter. Among the possible techniques utilized to generate this state, we present more particularly the coupling between static, using DAC (diamond anvil cell), and dynamic compression. It allows to move away from the principal Hugoniot curve and reach states which are closer to planetary isentropes. In this context, I shall present some recent direct applications to giant planetary cores experiments on water performed at various European laser facilities. Also knowledge of iron melting line at multimegabar pressures is fundamental for understanding the Earth's interior. Pressure-temperature measurements were obtained by studying partially released states of iron into a transparent lithium fluoride (LiF) window. The Fe/LiF interface velocity served as a pressure gauge while optical radiation through the window is fitted to a greybody function in order to deduce temperature. Experimental results related to iron fusion temperature at high pressures will be shown. Finally novel diagnostic techniques combining long pulses and short ultra intense beam will be discussed. (Author)