Journal of Quantitative Spectroscopy & Radiative Transfer 65 (2000) 83}90 Electron density dependence of dielectronic recombination in highly ionized atoms E. Behar*, R. Doron, P. Mandelbaum, J.L. Schwob, V.L. Jacobs Racah Institute of Physics, The Hebrew University, Jerusalem 91904, Israel Complex Systems Theory Branch, Code 6693, Condensed Matter and Radiation Science Division, Naval Research Laboratory, Washington, DC 20375-5345, USA Abstract A model is introduced for investigating the e!ect of electron}ion inelastic collisions on dielectronic recombination (DR) and predicting its electron-density dependence. A general method for obtaining e!ective DR rate coe$cients for optically thin dense plasmas is described. Level-by-level relativistic calculations are performed for DR of Ne-like iron. The results clearly show that, as the electron density increases, the "rst density e!ect is an enhancement of the DR rates through collisional transitions among the doubly excited autoionizing levels. At higher densities, collisional stabilization and collisional ionization play an important role. The former process enhances the DR rate, whereas the latter reduces it. It is found that the total collisional e!ect, which is a combination of the collisional mixing, collisional stabilization, and collisional ionization e!ects, is an enhancement of the DR rate coe$cients of Ne-like iron by a factor of 2 at an electron density of 10 cm and at an electron temperature of k¹  "200 eV. At lower temperatures (k¹  "100 eV), the total enhancement can be as much as one order of magnitude.  2000 Elsevier Science Ltd. All rights reserved. 1. Introduction Dielectronic recombination (DR) is the most important recombination process in highly ionized plasmas. The precise knowledge of the DR rates is essential for the calculation of the ionization balance and for the analysis of the dielectronic line intensities emitted from these plasmas. Consequently, there have been numerous investigations of DR in the past 30 years. Since the pioneering works of Burgess [1,2], many calculations for DR in complex atomic systems have been * Corresponding author. Tel.: 00-972-2658-5836; fax: 00-972-2658-5034. E-mail address: behar@vms.huji.ac.il (E. Behar) 0022-4073/00/$ - see front matter  2000 Elsevier Science Ltd. All rights reserved. PII: S 0 0 2 2 - 4 0 7 3 ( 9 9 ) 0 0 0 5 7 - 6