The CHIANTI database, a consistency check on the accuracy of the stored cross-section values in He i to O i isoelectronic sequence ions
CHIANTI is an atomic database with software for calculating emission properties. It is extensively used in deriving the atomic properties of spectra recorded from astrophysical and low density laboratory plasmas. In order to obtain an insight into the accuracy of the CHIANTI calculated level populations, a consistency check was conducted along the He i, Be i, B i, C i, N i, and O i isoelectronic sequences. In the evaluation process, levels of the ground configuration and the first and second excited configurations were considered. These are the levels responsible for most of the spectral lines used when deriving the plasma properties of astrophysical objects. As is documented below, the accuracy of the CHIANTI level population calculations depends on the particular ion, level and on the electron density. Under some conditions the calculations appear quite robust while in others they are not.