Saturated output of a GeXXIII x-ray laser at 19.6 nm

We report on measurements of the saturated single frequency output of a GeX X I I I x-ray laser on the J=0→1 transition at 19.6 nm from a refraction compensating double target driven by 150 J of energy from 75-ps Nd-glass laser pulses. The 19.6-nm line completely dominated the laser output. The output energy was measured to be 0.9 mJ in a beam of 6.6×30 ${\mathrm{mrad}}^2$ divergence, corresponding to a conversion efficiency of 6×${10}^{\mathrm{-}6}$. © 1996 The American Physical Society.