The use of mixtures of rare gases and metal vapors as active media for NPLs is of interest first of all in connection with the possibility of obtaining lasing in the visible and UV ranges of the spectrum. We note that lasing at a large number of transitions of metal ions and atoms was obtained in recombination mode with the excitation of active media using an electron beam and in a gas discharge afterglow (for example, see [18,109], and the literature cited there). This information helps in the search for NPL active media.

Virtually all of the experimental and theoretical research known to us concerning metal vapor NPLs was carried out in Russia. At VNIIEF, the possibility of using mixtures of rare gases with vapors of metals (Li, Na, Mg, Hg, Cd, etc.) as the NPL active media was considered from 1975 to 1976 [3].