Abstract: The dependence of the laser output energy on the upper level relaxation rate and pump rate at saturation intensity is numerically investigated. The relaxation rate of upper level is equal to the transition probability of stimulated emission. The Ar-Kr-F system with the argon pressure between four and six atm for four groups partial gas densities of Ar and F is investigated. For a given excitation rate and outcoupling, the output energy density and some parameters as a function of the krypton concentration are calculated.
The maximum output of laser energy requires maximum small-signal gain g₀, namely, the ratio of the pump rate to the upper level relaxation rate （R_p /k）, but also a maximum upper level relaxation rate. Finally, from the upper level relaxation rate and pump rate at saturation discussed, the optimized condition for partial gas densities, pressures and beam current densities are obtained.