We describe an experiment demonstrating XUV amplification following collisi
onal excitation in a discharge-created plasma waveguide irradiated by a pic
osecond optical laser pulse. A capillary discharge was used to generate a p
lasma radiation pipe with a radially concave electron density profile. Temp
orally resolved transmission characteristics and guiding effect have been m
easured. An intense short laser pulse rapidly heated the electrons, produci
ng amplification in the 3p(1)S(0)-3s P-1(1) transition of Ne-like S at 60.8
4 nm. The integrated gain-length product obtained within a 3 cm. active med
ium with a laser energy of 0.46 J was similar to6.8. The pump energy deplet
ion has been analysed as well. This new, hybridly pumped soft X-ray laser w
ith the transient gain offers a new way towards efficient tabletop coherent
XUV sources.