Extracting quantitative properties of radiative shocks on the National Ignition Facility

Radiative shocks occur throughout the universe in supernovae, supernova remnants, and accretion shocks. It is possible to create radiative shocks using high-energy laser facilities such as the National Ignition Facility (NIF).

Recent experiments on the NIF measured a radiative shock in 20 mg/cc CH foam using x-ray Thomson scattering (XRTS) and streaked, self-emission measurements. Sixty NIF beams drive a half-hohlraum to produce a radiation pulse that creates a pressure wave in solid polyimide that propagates as a radiative shock after breaking out into the foam. The self-emission data provides a time-resolved velocity measurement with an average of 130 km/s. Using a thick-thin shock model and an assumed upstream ionization allows one to calculate a shock temperature from the velocity measurement. Using the temperature mapping from the model comparison allows for a fit of the ionization in the upstream region and provides information about the preheat from the hohlraum. Fitting the XRTS data shows electron temperatures of several tens of eV at four different times over two shots and compares well with the self-emission results. This presentation will also show preliminary, quantitative findings of the shock cooling from these measurements.