Quasi-cw lasing due to the 4р — 4s transition of the argon atom in an He–Ar laser pumped by uranium fission fragments

An experimental investigation was made of the energy and threshold characteristics of an He–Ar laser (λ = 1149 nm) emitting radiation from the 4p[1/2]₁–4s' [1/2]₁⁰ transitioninthe argon atom. The maximum laser output power of 250 W, with an efficiency of ~ 0.1%, was obtained for an He:Ar = 250:1 mixture at a pressure of 2 atm. An analysis of the results showed that the 4s' [1/2]₁⁰ lower active level was deactivated due to collisional quenching by the helium atoms.