Long-term operation of a sealed CO2laser

The life expectancy of a sealed CO2laser tube depends, to a great extent, on the interaction of the molecules existing in the discharge at the cathode. The data reported here indicates that after operation of a sealed laser, only CO and O2are formed in concentrations comparable to the initial fill gases of CO2, N2, and He. The CO, CO2, and O2, in particular, were found to be completely adsorbed at the Ni cathode within several hundred hours of tube operation. A loss of 10.6 μm power output accompanied this adsorption. As expected, the process was reversible to a degree since the laser resumed operation at the initial power level after the cathode region had been heated to 300°C. This process of adsorption-desorption was repeated several times up to an accumulated operating time of 705 hours. During this time, the power output remained at a substantially constant value. However, the loss of CO2by carbon deposits ultimately means an end to tube life.