Study of neon-like lasing in gallium

We report the observation of lasing in neon-like gallium on the J=0-1, 2-1, and 1-1 transitions at 20.4, 24.7, 25.1, and 26.2 nm. The experiment was carried out on the Asterix TV iodine laser with and without a prepulse. It was found that without a prepulse, only weak lasing was observed on the J=2-1 transitions at 24.7 and 25.1 nm, and the J=0-1 transition at 20.4 nm, lased only marginally. The application of a prepulse 5.23 ns before the main pulse enhanced the J=0-1 laser output at 20.4 nm by two orders of magnitude. The pair of J=2-1 lasers were also enhanced. The gain coefficients were measured to be 4.3, 3.1, and 2.8 cm^-1 for the 20.4-, 24.7-, and 25.1-nm lasers, respectively. A comparison with germanium and zinc when no prepulse was used, illustrates the effect of the beam refraction on the J=0-1 and J=2-1 lasing as a function of the atomic number