EUV Spectra and Line Ratios of Multiply Ionized Calcium and Argon Atoms in a Laboratory Plasma

Abstract

The utility of Ca in the EUV spectral range of astrophysical observations is limited by a fragmentary and incomplete record of laboratory data. In order to obtain a more comprehensive survey of the Ca line emission in the EUV, we have used a tokamak plasma discharge in hydrogen carrying some Ar and intermittently seeded with Ca as a tool for investigating the emission line intensity pattern of highly charged Ca and Ar ions in the wavelength range 100–285 Å with 0.35 Å spectral resolution. We compare our data to wavelengths and line ratios in much-used databases, especially CHIANTI, and we discuss apparent inconsistencies.