Deexcitation and recombination of excited ions through doubly excited levels in a dense recombining plasma: Lithiumlike recombining plasma laser

Collisional transitions from excited levels in a dense recombining plasma have been considered for lithiumlike ions. Deexcitation from a level of the lithiumlike ion is enhanced by a process in which berylliumlike ions in doubly excited levels in local thermodynamic equilibrium with respect to this level autoionize. Excited ions may recombine through a process similar to the collisional-radiative (CR) recombination as in the case of ions in their ground states. We have estimated the effective rate coefficients for these processes by adopting various approximations. We have incorporated these approximations into our CR model code for lithiumlike aluminum ions in a high-density recombining plasma. The excited level populations and the amplification gains of several laser transitions are calculated for typical conditions of the recombining plasma laser. For an electron temperature of 5 eV, the gains of the 3d D-2-5f F-2 and 3d D-2-4f F-2 transitions are consistent with the experimental results.