Long-term operation of a sealed CO2laser

The life expectancy of a sealed CO
2
laser 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 O
2
are formed in concentrations comparable to the initial fill gases of CO
2
, N
2
, and He. The CO, CO
2
, and O
2
, 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 CO
2
by carbon deposits ultimately means an end to tube life.