100s Mbar equation of state measurements on the National Ignition Facility – platform development

The Multi-Material Equation of State platform on the National Ignition Facility has produced high quality data for materials of interest over the past few years. It was proposed to reduce the size of the driving hohlraum, in order to access an increased pressure regime. This modified platform, dubbed Planar High Pressure, or PHP, was fielded as a joint LLNL and AWE endeavour, with an initial proof of concept shot in January 2023. This platform uses a hohlraum of diameter 3.5 mm, compared with an original 6 mm. It was hoped that a reduced hohlraum size would allow us to increase the x-ray flux driving the physics package. The first PHP shot aimed to study gold at 100s Mbar pressures. First the physics package is driven to 100s Mbar with a steady, planar shock. VISAR is then employed to measure the shock velocity in gold, reference material molybdenum and a quartz window. This poster will detail the design of the platform and drive characterization data.