A spectroscopy diagnostic of plasma gradients in inertial confinement fusion imploded cores (abstract)

Abstract

X-ray spectroscopy of laser-driven imploded inertial confinement fusion (ICF) cores has proven to be a powerful diagnostic of spatially averaged temperature and density plasma conditions at the collapse of ICF implosion experiments. Temperature and density time histories can be extracted from the analysis of time-resolved x-ray line spectra using the temperature and density sensitivity of line intensities and Stark-broadened line shapes. The next step in the spectroscopy of imploded cores is the bracketing of core plasma gradients as a function of time. To this end, we discuss a spectroscopy diagnostic which is based on the self-consistent and simultaneous simulation and analysis of time-resolved x-ray line spectra and x-ray monochromatic images. Abel inversion of x-ray monochromatic images provide line emissivity spatial profiles; this information is critical for the determination of gradients in the core. We apply this technique to the analysis of data recorded in Ar-doped ICF implosion experiments driven with the GECCO XII laser system at Osaka University. In these experiments, time-resolved x-ray line spectra and x-ray monochromatic images were simultaneously recorded for the Ar He β and Ly β spectral features. From the analysis of the data we can extract the time history of temperature and density gradients in the core through the collapse of the implosion.