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%.