High-pressure sealed CW CO2laser with high efficiency

Discharge stabilization, long-term operation, output power characteristics, and efficiency of the high-pressure CW CO
2
laser have been investigated under sealed conditions. A comparison is made with low-pressure CW CO
2
lasers. Two types of electrode structures suitable for operations in the pressure range 100-760 torr are presented. Effects of O
2
and CO on the discharge stability and unsaturated gain are described. By using molecular sieve
3A
as an adsorbent of water vapor, which was the most detrimental impurity, sealed operation with no decrease in output power was achieved at 0.5-1.5 kW for more than 150 h elapsed time including about 30 h of discharge time. It has been demonstrated that high efficiency can be obtained in spite of high-pressure and sealed operation. The efficiency was improved by reducing the cavity loss due to the absorption of intracavity radiation by CO
2
molecules in the unexcited region, and by finding the optimum of gas mixture. A maximum efficiency of 19 percent was obtained at a 1 kW power level for a 100 torr gas mixture of either CO
2
-CO-N
2
-He = 2-1-19-19 or CO
2
-CO-N
2
-He-Ar = 2-1-18-10-10. The effects of Ar and N
2
proportion on the unsaturated gain and saturation parameter are discussed.