On the consistency of spectroscopic ion density measurements

A comparison between two different quantitative spectroscopic measurements of the ion density of He-like carbon C4+ has been performed and used as a consistency check of a collisional-radiative model. The C4+ ion density was calculated from a zero-dimensional excitation and ionization balance for a resonant vacuum ultraviolet transition in Li-like carbon C3+. This was compared with a one-dimensional excitation balance for a non-resonant ultraviolet transition in C4+. At stable plasma conditions the two methods give consistent results. (author)