Instantaneous population densities of the excited levels of hydrogen atoms and hydrogen-like ions in plasmas

Abstract

The statistical rate equations for the number densities of excited atomic (ionic) states have been solved for atomic hydrogen and hydrogen-like ions assuming a non L.T.E. distribution between states of different principal quantum number but statistical equilibrium amongst the sublevel populations belonging to a given principal quantum number. The calculations have been performed for the optically thin as well as for three different degrees of optical reabsorption. A detailed analysis of existing cross-section data is included. The numerical results are listed in tables containing the two-dimensionless global excitation coefficients r( 0) z−1 , j and r( 1) z−1 , j from which the absolute instantaneous populations are obtained. A new set of collisional-radiative recombination and ionization coefficients is presented in graphical form. Comparison with existing literature values for the optically thin case shows discrepancies which exceed a factor of two at low and medium electron densities at nearly all electron temperatures.