Direct mass spectrometric diagnostics for a CO2 gas laser

Abstract

An extremely small hole of approximately 10 μm in diameter was made on a glass plate by a special technique. Using this small hole, together with a turbomolecular pump, a pressure difference of seven orders of magnitude was achieved. Using this system, a direct analysis of the gas components in CO₂ lasers of 300‐mm‐long waveguide type and 800‐mm‐long common type during their short‐term lifetime has been performed. The following results were obtained: (1) In the case of filling with pure CO₂, a direct mass‐spectrometric analysis of CO₂ decomposition process has been performed showing a decomposition of 80% in partial pressure. (2) In the case of filling with pure CO, the continuous increase of CO₂ was observed, and an equilibrium CO₂ peak height of about 8% of the total peak height was reached. (3) In the case of filling with a laser gas mixture, the variations of all components were observed, and an analysis of the curve shapes showed that there exists a cataphoresis effect. (4) When a procedure of ‘‘discharge‐rest–discharge‐rest’’ was used, the results were different for anode sampling and for cathode sampling. This proves cataphoresis action occurs. The technique presented in this paper should be valuable to the study of neutral dissociation and recombination mechanisms within gas lasers.