Interface velocity of laser shocked Fe/LiF targets

The interface velocity of iron partially releasing into a lithium fluoride (LiF) window has been measured using VISAR technique. Corrections to the fringe-per-velocity relationship are presented. A good agreement with hydrodynamic simulations is found at laser intensities <2×1013 W/cm2. For higher intensities, velocities appear to be lower than the numerical predictions. A strong modification of compressed LiF index of refraction behavior might explain such a discrepancy.