Spectral Lines of Highly-ionized Atoms for the Diagnostics of Fusion Plasmas

Spectral lines emitted from the different ionization stages of various elements present (either naturally occuring or deliberately added) in high-temperature tokamak plasmas may be used for localized diagnostics of such plasmas. This fact has motivated a search for transitions suitable for these purposes. Such transitions are of essentially two types: Δ n = 0 resonance transitions (in particular of one- and two-valence electron systems) and magnetic dipole transitions arising within the ground configurations of ions of highly-ionized, high- Z elements. The latter transitions are peculiar to the fairly low-density, quasisteady plasmas prevailing in tokamaks – and to celestial plasmas. In this paper we review the progress that has been made in the line identification program, paying particular attention to the high- Z members of the isoelectronic sequences of the second period. For these sequences, critical examinations of measured data and comparisons with theoretical calculations have been carried out by Professor Bengt Edlén, resulting in highly accurate wavelength predictions.