Collisional radiative model including dielectronic states

Abstract

We have constructed a collisional radiative model of two-electron ions including dielectronic states 2s nl and 2p nl as well as singly excited states 1s nl. We formulate for transition rate coefficients assuming a quasi-steady state with the independent states 1s 2, 1s, 2s and 2p. Using this formulation we derive effective transition rate coefficients among the independent states 1s 2, 1s, 2s and 2p; these are effective ionization, recombination, excitation and de-excitation coefficients. We study the effects of collisions 2s nl↔2p nl and 1s nl↔2l’ nl and find that the 1s nl↔2p nl transitions have a large effect on the population densities of dielectronic states, on the effective excitation/de-excitation rate coefficients and on satellite line intensities.