The gain distribution of the transient collisional excited X-ray lasers

An atomic kinetics model of an electron collisional excited X-ray laser is developed, and the spatial and temporal evolution of the soft X-ray gain is investigated. The calculation of the gain agrees with experiment for the t ransient collisional excited (TCE) Ni-like Ag laser (lambda = 139 Angstrom) pumped by two 100 ps laser pulses. The mechanism of producing gain in the ionizing plasma is discussed. The calculation is applied to the optimizatio n of the gain. It is found that higher gain can be obtained by pumping a th in foil target with 2 ps laser pulses. The saturation intensity of the X-ra y lasers is also investigated through the analysis of the detailed atomic p rocesses of the upper laser level. (C) 2001 Elsevier Science Ltd. All right s reserved.