Gain characteristics of a multiatmosphere UV-preionized CO2laser

The small-signal gain of a transverse-discharge UV-preionized CO
2
laser has been investigated at pressures in the 1-15-atm range. Measurements were carded out on the
P(18)
and
R(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
^-1
are 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 both
R
branches increases more rapidly with pressure than that of the
P
branches, 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.