Dielectronic Satellite Spectra for Highly-Charged Helium-Like Ion Lines

Abstract

Calculations have been carried out in intermediate coupling of the wavelengths and intensities of the satellite lines situated on the long wavelength side of the helium-like ion resonance lines, recently observed from solar flares. Earlier calculations up to aluminium have been extended up to iron and copper. For the intensities, the important processes are primarily dielectronic recombination, but also direct inner-shell excitation. Comparisons have been made with spectra from solar flares and active regions, and from low-inductance laboratory sparks. Computed wavelengths in iron are found to agree with these to better than 0.0003 Å. Comparison of the intensities allows the determination of both the electron temperature and the transient ionizing state of the plasma. The laboratory plasma spectra are found to be in an extreme transient ionizing condition, and are thus significantly different from solar spectra. In the cases studied, solar active regions were found to be moderately ionizing, while the flare spectra were recombining.