EOS Measurements Using Refractive Enhanced Radiography of Cylindrically Converging Shock Waves**

We have developed an experimental platform for streaked refractive enhanced radiography (RER) [1] of cylindrically converging shock waves at the National Ignition Facility (NIF) for equation of state (EOS) measurements along the principal Hugoniot for low-Z elements with reduced bound-free absorption contrast. In addition to leveraging refraction enhancement to infer shock compression, RER enables high precision shock trajectory measurements including the rebound shock.

The shock waves are indirectly driven in 6.72 mm diameter gold hohlraums using a radiation drive adapted from the Gbar platform [2], generated with a 4 ns long square-shaped, 0.5 MJ laser drive. Due to convergence effects, the shock waves increase in strength and allow to probe a range of shock pressures (50 – 150 Mbar) in a given experiment. The first experiments used plastic and LiH cylinder samples with up to 1.4 mm diameter. We will report on first results from experiments at the Omega and NIF laser facilities.

 

[1] D.S. Montgomery, Rev. Scient. Instrum. 94, 021103 (2023).

[2] T. Doeppner et al., Phys. Rev. Lett. 121, 025001 (2018).