Modeling conditions of radiative heat waves in the Xflows NIF experiment

The Xflows NIF experiment seeks to create and study radiative heat waves in Silica aerogel foams using a novel spectroscopic temperature diagnostic technique [1]. By including titanium in the foam and using broadband absorption spectroscopy, one can infer the ionization state and temperature in the foam as the wave passes through it. Xflows on NIF is the successor to the COAX campaign [2] on the Omega-60 laser which used x-ray radiography and absorption spectroscopy to better understand radiation

transport in HED systems. On NIF, Xflows has access to higher temperature regimes with stronger shocks and supersonic radiation waves. This work will present Xflows shots with a radiative heat front in ∼100 mg/cc aerogel foam cylinders driven by a gold hohlraum in a “T-raum” configuration. We will describe a computational study to predict the performance of the hohlraum and how radiation propagates in the foam. Simulations indicate that the hohlraum creates a spatially and temporally uniform radiation source of approximately 280 eV which is incident on the foam and creates a heat front propagating at speeds peaked near 1000 km/s. These simulations will be compared to experimental radiographs and

absorption spectroscopy of the wave traveling through the foam.