Population of Excited Levels of Atoms and Ions: Electron Temperature and Density from Relative Line Intensities of the Ions C IV, N V and O VI

The theory of the population of excited levels for atoms and ions is given for stationary, nonthermal plasmas. Simplified expressions were obtained, with the aid of which populations of the levels $2P$, $3P$, and $3D$ were determined for the ions C IV, N V, and O VI. It is shown that the populations obtained by this method are in very good agreement with the populations determined directly from the balance of excitation and de-excitation processes. Plots are given which enable the determination of electron density and temperature from relative intensities of three chosen lines from a given ion.