Feasibility of generation of VUV stimulated radiation utilising resonant levels of ions populated by charge-transfer reactions

An analysis is made of the feasibility of constructing a VUV laser which utilises the reaction of charge transfer between neon ions and rubidium atoms. The example of an Ne$^+$ – Rb mixture is used to show that a population inversion can be established between resonantly excited and ground levels of the rubidium ion when a neon-ion beam strikes a target of rubidium atoms. It should be possible to reach a VUV radiation energy of up to $\sim 0.4~\mu$J per pulse at the wavelength 71.1 nm. Experiments show that the cross section of the charge-transfer reaction is ($2 \pm 0.5)\times 10^{-15}$ cm$^2$ and that efficient excitation of the upper active level ($5s[1/2]^0_1$) of Rb$^+$ is possible in a plasma formed from an Ne – Rb mixture.