Lasing on the IR transitions in krypton and argon atoms due to excitation of active media with uranium fission fragments

Binary and ternary high-pressure He–Kr(Ar), Ne–Kr(Ar), Ne–Kr(Ar)–He mixtures and pure Kr were excited by uranium fission fragments. Quasi-cw lasing on the 1.78, 1.87, 2.19, 2.52, 2.63, 2.86, and 3.07 μm lines of the Kr atom and on the 2.06, 2.10, 2.21, 2.31, 2.40, and 2.87 μm lines of the Ar atom was recorded. Nuclear-pumped lasing on the 2.06, 2.10, 2.21, 2.31, 2.63, and 2.86 μm lines was observed for the first time and the 1.87 and 2.87 μm lasing lines were entirely new. The lasing characteristics were optimised by varying the composition of the mixtures. The highest energy parameters (output radiation power ~450 W, efficiency ~0.6%) were obtained for He–Kr (λ = 2.52 and 3.07 μm) and Ne–Kr–He (λ = 2.19, 2.52, 2.86, and 3.07 μm) mixtures. The lowest lasing thresholds obtained for the thermal neutron fluxes of about 2×10¹³ cm^-2 s^-1 were recorded for the 1.78 μm line emitted by an Ne–Kr–He mixture and for the 2.63 μm line of pure Kr.