Gain characteristics of a multiatmosphere UV-preionized CO2laser

The small-signal gain of a transverse-discharge UV-preionized CO2laser has been investigated at pressures in the 1-15-atm range. Measurements were carded out on theP(18)andR(16)lines of both the 10.4- and 9.4-μm bands, and data on the pressure dependence of the peak gain and gain rise time are presented. The results demonstrate that small-signal gains in excess of 5-percent cm-1are readily obtained at pressures of ∼ 12 atm and confirm that the relaxation times of the energy levels relevant to laser action scale inversely with pressure. In addition, it is found that the gain of bothRbranches increases more rapidly with pressure than that of thePbranches, while there are indications that the 9.4- and 10.4-μm gain values become comparable at pressures of ∼ 15 atm. The experimental results have been compared with the dependence of gain on pressure predicted by a relatively simple theoretical model. On the basis of this model it is found that the experimentally determined gain rises more rapidly with pressure than one would expect and a number of possible reasons for this discrepancy are discussed.