Hybridly pumped collisional soft X-ray laser in Ne-like sulphur

We describe an experiment demonstrating XUV amplification following collisional excitation in a discharge-created plasma waveguide irradiated by a picosecond optical laser pulse. A capillary discharge was used to generate a plasma radiation pipe with a radially concave electron density profile. Temporally resolved transmission characteristics and guiding effect have been measured. An intense short laser pulse rapidly heated the electrons, producing amplification in the 3p 1 S 0 -3s 1 P 1 transition of Ne-like S at 60.84 nm. The integrated gain-length product obtained within a 3 cm active medium with a laser energy of 0.46 J was -6.8. The pump energy depletion has been analysed as well. This new, hybridly pumped soft X-ray laser with the transient gain offers a new way towards efficient tabletop coherent XUV sources.