Parametric studies for bound state excitation in ion-ion collisions related to gain modeling of X-ray lasers with Li-like ions

The gain modeling of X-ray lasers has been concentrated up to now to electron-impact and decay processes, the rate coefficients of which have important role in density distribution on excited levels. In the particular case of recombination X-ray lasers the electronic temperatures cover a wide range, between several hundreds of eV to 30-50 eV. Frequently, the gain is determined at low temperature when the populations of the 41 and 51 levels have the maximum value. Then when plasma electrons and ions have comparable temperatures the role of ion-impact excitation could have a similar effect in redistributing population among the excited states. This paper is devoted to parametric studies on the ion-impact excitation cross section for the 1s(2) 31 and 1s(2) 41 transitions involved in population inversion related to X-ray lasers with Li-like, aluminum ions.