Analysis of time-resolved argon line spectra from OMEGA direct-drive implosions

Abstract

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 870μm in diameter, 27μm wall thickness plastic shells filled with 20atm 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 3100to4200eV 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.