X-ray laser gain measurements in a collisionally excited germanium plasma

We have used a novel beam-averaging technique that makes use of a segmented wedge array (SWA) to overlap several line foci and to produce a much more uniform linear plasma than has been obtained to date. With this focusing arrangement, laser gain was observed for the first time to our knowledge on a 2s2p63d–2s2p63p, J = 2–1 Ne-like transition at 198.99 Å. The experiments were carried out on the LP2 Nd:glass laser system operating at 1.06 μm with incident energies of ~125 J/cm of line focus. We also observed gain on five 3p–3s transitions, using both the SWA and crossed cylindrical lenses to produce the line focus.