Characterization of laser-driven ultrafast shockless compression using gold targets

Indirect laser-driven shockless compression experiments on gold targets were performed to characterize pressure loading processes and target states. Free surface velocities of the gold target under ramped pressure loading were measured using line-imaging velocity interferometers. From the velocity data and the equation of state, the maximum pressure and strain rate attained under compression were estimated to be ∼50 GPa and ∼4 × 10⁷s⁻¹, respectively. Optical reflectivity was measured simultaneously with the velocity, the result suggesting no significant or unexpected temperature increases in the ultrafast shockless compression process.