Abstract. Effective recombination coefficients are given for C ii transitions between doublet states. The calculations are carried out in the temperature range 500 − 20 000 K and for an electron density of 10 4 cm −3 . The effects of electron collisions on the excited states are included. The necessary bound-bound and bound-free radiative data are obtained from a new R-matrix calculation in which photoionization resonances are fully delineated, thereby accurately incorporating the effects of both radiative and dielectronic recombination. The R-matrix calculation includes all bound states with principal quantum number n ≤ 15 and total orbital angular momentum L ≤ 4. The effect of moving the resonance features to their experimentally determined positions is also investigated and found to be important at low temperatures.

Abstract. We calculate effective recombination coefficients for the formation of selected lines of N ii. New photoionization data are computed which accurately map the near threshold resonances and are used to derive recombination coefficients for principal quantum numbers, n ≤ 15, including radiative and dielectronic recombination. Cascading from higher states is included, allowing for the effects of finite electron density in a hydrogenic approximation. The effects of population in the excited states of the recombining ion are investigated.

The charge state distributions of Fe, Na, and F are determined in a photoionized laboratory plasma using high resolution x-ray spectroscopy. Independent measurements of the density and radiation flux indicate unprecedented values for the ionization parameter xi=20-25 erg cm s(-1) under near steady-state conditions. Line opacities are well fitted by a curve-of-growth analysis which includes the effects of velocity gradients in a one-dimensional expanding plasma. First comparisons of the measured charge state distributions with x-ray photoionization models show reasonable agreement.

Abstract. We calculate total recombination coefficients for Ne 2+ + e − and effective recombination coefficients for the formation of selected lines of Ne ii. New photoionization data are calculated which accurately map the near threshold resonances and are used to derive recombination coefficients for principal quantum numbers, n ≤ 15, including radiative and dielectronic recombination. Cascading from higher states is included, allowing for the effects of finite electron density in a hydrogenic approximation. The effects of population in the excited states of the recombining ion are investigated.