12.8-ev Laser in Neutral Cesium

Abstract
We report the operation of a saturated 96.9-nm laser in Cs vapor that has an extrapolated small-signal gain of exp(83) in a total length of 17 cm. We believe that lasing occurs from a core-excited level embedded in the continuum of the valence electron. The laser is pumped by soft x rays from a synchronous, traveling-wave, laser-produced (2.5 J, 20 ps, 1064 nm) plasma.