X-ray laser studies at LLE

New target geometries for collisional excitation X-ray laser experiments (in nickel) were proposed, analyzed, and experimentally studied on the glass development laser. The new geometries are designed to yield a higher gain and reduced refraction due to (1) a higher plasma density, (2) a wide lateral density profile, and (3) a concave lateral density profile. These new geometries were (a) two parallel exploding (thin) foils, irradiated from one side only, (b) two ablating (thick) foils, one of which was irradiated on its inner face, and (c) and exploding foil in front of an ablating foil, irradiated by a single laser beam incident on the thin foil. Long-line-focus experiments are described. Theoretical developments included development of a ray-tracing code for an amplifying medium of varying lateral density profile and prediction of high gain on new type transitions in neon-like ions, involving the excitation of an inner (2 s) electron