Amplification of extreme ultraviolet (XUV) radiation at wavelengths about 50 nm in a recombining z-pinch plasma is reported. Discharge currents of 40 kA were used to produce highly uniform plasma columns with a diameter of less than 500 μm and a length of up to 9 cm. During the expansion of the pinch plasma, amplification at the 4f-3d and 4d-3p transitions of lithiumlike oxygen OVI was observed. The gain-length products were determined to be 2.5 (4f-3d) and 2.2 (4d-3p), corresponding to gain coefficients of 0.28 and 0.24 ${\mathrm{cm}}^{-1\mathrm{}}$, respectively.

• Received 28 November 1995

DOI:https://doi.org/10.1103/PhysRevLett.76.3124