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 P-1(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 similar to6.8. 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.