Demonstration of a Discharge Pumped Table-Top Soft-X-Ray Laser

We report the first observation of large soft-x-ray amplification ($gl=7.2$) in a discharge-created plasma. A fast, {~}40 kA, current pulse from a compact discharge was used to excite plasma columns up to 12 cm in length in 4-mm channels, producing population inversion in the J=0-1 line of Ne-like Ar and resulting in a gain of 0.6 cm^-1 at 46.9 nm. The beam divergence was measured to be 9 mrad.