Gain characteristics of a multiatmosphere UV-preionized CO<inf>2</inf>laser

Abstract

The small-signal gain of a transverse-discharge UV-preionized CO <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> laser has been investigated at pressures in the 1-15-atm range. Measurements were carded out on the <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">P(18)</tex> and <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">R(16)</tex> 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 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> 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 <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">R</tex> branches increases more rapidly with pressure than that of the <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">P</tex> 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.