Amplification of extreme-ultraviolet radiation in a gas-liner pinch plasma

The emission of the 4f-3d and of the 4d-3p spectral lines of the Li-like ions C iv, N v, O vi, and F vii is studied in a gas-liner pinch plasma. For O vi the comparison of radial and axial line intensities reveals clearly amplification of the 4f-3d transition at 51.97 nm in the axial direction corresponding to a gain-length product of G=gl=4.5. The corresponding transition in F vii at 38.18 nm is enhanced already in the radial direction by factors up to 4.6. The strongest amplification always occurs at times shortly before maximum pinch compression.