Plasma interpenatration study on the omega laser facility

The Near Vacuum Campaign on the National Ignition Facility has sparked an interest on the nature of the gold/carbon interface at high velocity (400 km/s), high electron temperature (2 keV), low-electron density (1e21). Indeed radiation-hydrodynamic simulations using the code HYDRA have been unable to accurately reproduce the experimental shape of the hot spot resulting from implosion driven in Near Vacuum Holhraum. The experimental data are suggesting that the NIF inner beams are freely propagating to the waist of the hohlraum when the simulations predict that a density ridge at the gold/carbon interface blocks the inner beams. The discrepancy between experimental data and simulation might be explained by the fluid description of the plasma interface in a rad-hydro code which is probably not valid in when two plasma at high velocity, high temperature are meeting in a Near Vacuum Hohlraum. To test our assumption that a kinetic description is more appropriate in this regime, we went to the Omega laser facility to study gold/carbon interface in the relevant regime. We will present results comparing the plasma interface of a C/C, Al/C and Au/C under the same laser drive. Time resolved images of the self-emission of the interface as well as Thomson scattering data will be presented.