Fig. 5: Velocity of the Ni/LiF interface versus time traces for run 097 (LV13, red), run 099 (LV13, blue), and run 493 (L10075, black).

Solid traces represent data from VISAR 1, and dashed traces represent data from VISAR 2. Shaded regions reflect the standard deviation of the calculated particle velocity. Time is normalized to arrival at the Ni/LiF interface. Here, the transmitted compression waves are described by a fast initial rise, after which there is a distribution of velocity states up to a peak value. At late times, the velocity drops off due to a stress release associated with the end of the applied laser drive. Temporal unsteadiness in the peak compression state is attributed to non-ideal laser pulse shaping, reverberations within the epoxy glue layers of the sample, and, at late times, a reverberation within the Ni foil itself (this is visible 1.5 ns after breakout in run 493). Note that expected transit times of the shock through the Ni foil for each run are presented in Table 1, and range from 2.90 ns for run 097 to 1.16 ns for run 493. Determination of the average shock stress and distribution of stress states includes the range of velocity states above the initial shock. Error is shown as the shaded region surrounding each trace. Arrows indicate the region over which the range of velocities was considered, taking into account the transit times listed in Table 1 for each run.