RADIATION TRAPPING AND X-RAY LASING IN AL10+ IN THE RECOMBINATION SCHEME

A self-consistent model for radiation trapping in recombining plasmas is presented in view of X-ray laser gain calculations. We obtain the population density of the lasing levels in the presence of resonance photons which are emitted from the lower level of the lasing transition and which may be reabsorbed elsewhere in the plasma. The resulting gain reduction at the time and in the cell of maximum gain is about 25% and 10% for the Li-like Al transitions at 154.7 and 105.7 Angstrom, respectively. Our results for the transition at 154.7 Angstrom agree to within 10% with the most recent measured gain, in contrast with the up-to-date calculations on the escape probability which predict much smaller gains.