Collision frequency measurement from optical reflectivity of laser indirect-driven CH/Al/Diamond

A collision frequency measurement from the optical reflectivity of laser indirect driven CH/Al/Diamond on the SG-10kJ laser facility is presented. The optical reflectivity and the Al/diamond interface velocity were measured simultaneously by the velocity interferometer. The aluminum rear surface density was deduced from the interface velocity by analyzing the wave interaction. The deduced sample state was compared with the simulation and quite good agreement was found. The electron collision frequency was deduced by fitting the sample state to the optical reflectivity, and it is found that the experimental collision frequency agrees with a semi-empirical result within the error bar, but is larger than the simulated result based on the average-atom model with the hypernetted chain approximation.