Catalytic converters for closed-cycle operation of isotopic CO2 TEA lasers

Abstract

Long‐term operation of high‐power rare isotope CO₂ TEA lasers operating with high CO₂ concentrations (20%–25%) has been achieved using a variety of Pt and Pt‐coated catalysts to drive the CO+1/2O₂→CO₂ recombination reaction. The problem of oxygen exchange between ¹⁸O substituted CO₂ species (628, 828, 838, etc.) and the heated catalysts, or their supporting substrates, has been studied closely. It was found that Pt over an aluminum washcoat on a stainless steel substrate provided good catalytic activity with negligible oxygen exchange, if the Pt to Al₂O₃ mass ratio was near unity. Catalytic converter performance was analyzed for a typical laboratory CO₂ TEA laser (Lumonics 103) with a measured O₂ generation rate of ∼0.15 liter Torr per liter of discharge volume per pulse. The laser output was correlated to the catalytic converter operating temperature, as well as the equilibrium O₂ concentration. Laser performance was typically degraded for O₂ concentrations in the discharge in excess of 0.1%.