Radiation Drive Designed to Extend the Pressure Ranges Measured inGbar Equation of State Experiments at the National Ignition Facility

We present the design and demonstration of a new radiation temperature drive to increase the

pressure range measured using the existing Gbar experimental platform at the National Ignition

Facility. Using the same peak radiation temperature as data previously published spanning 25–60

Mbar in polystyrene [1], post-shot hydrodynamic simulations suggest the new drive can measure 20–

200 Mbar with the same target design. The drive starts with a low radiation temperature that launches

a weak shock into the sample and is followed by a continuous increase in radiation temperature to

strengthen the leading shock. The additional shock strengthening elevates the pressures within the

sample beyond what is achievable by convergence alone. Design features of the new drive and

accompanying radiation hydrodynamics simulations are used to illustrate the method in which the

pressure range was increased. The design of this drive can be used to significantly increase the

amount of equation of state data collected on each experiment.

[1] T. Döppner et al, Phys. Rev. Lett. 121, 025001 (2018).