Spectroscopy and atomic physics of highly ionized Cr, Fe, and Ni for tokamak plasmas

Abstract

We consider the spectroscopy and atomic physics for some highly ionized Cr, Fe, and Ni ions produced in tokamak plasmas. Specifically, we consider both allowed and forbidden transitions between levels of the 2s22pk, 2s2pk+1, and 2pk+2 configurations. Forbidden and intersystem wavelengths for Cr and Ni ions are extrapolated and interpolated using the known wavelengths for Fe lines identified in solar-flare plasmas. We present tables of transition probabilities for the B I, C I, N I, O I, and F I isoelectronic sequences, and give collision strengths and transition probabilities for Cr, Fe, and Ni ions of the Be I sequence. Proton excitation rate coefficients for fine-structure transitions in the Be I through F I sequences are tabulated, as well as populations of all levels of the 2s22pk, 2s2pk+1, and 2pk+2 configurations for Cr, Fe, and Ni for the Be I sequences, and for Cr and Ni for the B I-F I sequences. We discuss similarities of tokamak and solar spectra, and show how the atomic data we have presented may be used to determine ion abundances and electron densities in low-density plasmas.