Search

Abstract: We discuss calculations of synthetic spectra for the interpretation and analysis of K-shell and bound-free emission from argon-doped deuterium-filled OMEGA direct-drive implosion cores. The spectra are computed using a model that considers collisional-radiative atomic kinetics, continuum-lowering, detailed Stark-broadened line shapes, line overlapping, and radiation transport effects. The photon energy range covers the moderately optically thick n =3→ n =1 and n =4→ n =1 line transitions in He- and H-like Ar, their associated satellite lines in Li- and He-like Ar, and several radiative recombination edges. At the high-densities characteristic of implosion cores, the radiative recombination edges substantially shift to lower energies thus overlapping with several line transitions. We discuss the application of the spectra to spectroscopic analysis of doped implosion cores. [Copyright &y& Elsevier]

Detailed analysis of x-ray narrow-band images from argon-doped deuterium-filled inertial confinement fusion implosion experiments yields information about the temperature spatial structure in the core at the collapse of the implosion. We discuss the analysis of direct-drive implosion experiments at OMEGA, in which multiple narrow-band images were recorded with a multimonochromatic x-ray imaging instrument. The temperature spatial structure is investigated by using the sensitivity of the Lyβ/Heβ line emissivity ratio to the temperature. Three analysis methods that consider the argon Heβ and Lyβ image data are discussed and the results compared. The methods are based on a ratio of image intensities, ratio of Abel-inverted emissivities, and a search and reconstruction technique driven by a Pareto genetic algorithm. [ABSTRACT FROM AUTHOR]

We present results from the spectral postprocessing of a one-dimensional hydrodynamic simulation of an argon-doped, warm-shell shock-ignition implosion with a detailed atomic and radiation physics model. The argon tracer is added to the deuterium filling in the core for diagnostic purposes. Spectral features in the emergent intensity distribution in the photon energy range of the argon K-shell spectrum that have potential for diagnostic application are discussed. [ABSTRACT FROM AUTHOR]

We discuss the observation and data analysis of argon K-shell line spectra from argon-doped deuterium-filled OMEGA direct-drive implosion cores based on data recorded with two streaked crystal spectrometers. The targets were 870 μm in diameter, 27 μm wall thickness plastic shells filled with 20 atm of deuterium gas, and a tracer amount of argon for diagnostic purposes. The argon K-shell line spectrum is primarily emitted at the collapse of the implosion and its analysis provides a spectroscopic diagnostic of the core implosion conditions. The observed spectra includes the Heα, Lyα, Heβ, Heγ, Lyβ, and Lyγ line emissions and their associated He- and Li-like satellites thus covering a broad photon energy range from 3100 to 4200 eV with a spectral resolution power of approximately 500. The data analysis relies on detailed atomic and spectral models that take into account nonequilibrium collisional-radiative atomic kinetics, Stark-broadened line shapes, and radiation transport calculations. [ABSTRACT FROM AUTHOR]