Optogalvanic effect in a CO laser

An experimental investigation was made of the influence of lasing on the populations of vibrational CO levels, on the gas temperature, and on the electrical parameters of a longitudinal discharge in a continuous-flow CO laser with cryogenic cooling. The observed changes in the electrical parameters of the discharge could be explained on the assumption that the main ionization process in the absence of lasing was the reaction CO(ν > 14) + CO* → (CO)₂⁺ + e (where CO* is the carbon monoxide molecule in the highly excited metastable state I ¹∑). Lasing suppressed this reaction, which increased the ratio E /N and the voltage across the discharge, and also reduced the discharge current.