Effects of postcapture electron-ion collisions on dielectronic recombination demonstrated on Ne-like ions - art. no. 062708

A model is introduced for investigating the effect of electron-ion inelasti c collisions on dielectronic recombination (DR) and for predicting its elec tron-density dependence. A general method for obtaining effective DR rate c oefficients for optically thin dense plasmas is described. Level-by-level r elativistic calculations are performed for DR of Ne-like iron, selenium, an d tungsten in their ground state via the Na-like 1s(2)(2s2p)(7)3l n' l' (n' = 3,4) autoionizing configurations. The results clearly show that, as the electron density increases, the first density effect to appear is an enhanc ement of the DR rates through collisional transitions among the autoionizin g levels. At higher densities, collisional stabilization and collisional io nization play an important role. At low electron temperatures, collisional stabilization processes enhance the DR rates, whereas at high temperatures, collisional ionization reduces them. However, in a relatively wide interme diate temperature range, the opposite contributions of the various collisio nal mechanisms can result in a very small total collisional effect. Additio nally, it is found that all of the various collisional effects strongly dec rease with the ion charge. For very highly charged ions, such as Ne-like W, the collisional effect is appreciably quenched, even at very high densitie s, due to the dominance of the radiative processes.