Demonstration of a discharge pumped table-top soft X-ray laser

We report the first observation of large soft X-ray amplification (g*1=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 capillary discharge excitation scheme has the potential for increasing the wall-plug efficiency of ultrashort wavelength lasers by two orders of magnitude