Relative merits of using curved targets and the prepulse technique to enhance the output of the neon-like germanium X-ray laser

We present a series of experiments using germanium slab targets with either flat or curved surfaces which are illuminated by a low intensity prepulse before the main optical drive pulse of the 1.315 mu m Asterix iodine laser. By varying the radius of curvature of the target surface and the size of the prepulse we show the relative merits of these two effects on improving the output of the neon-like germanium 3p(1)S(0) --> 3s(1)P(1) lasing transition at 196 Angstrom. While the curved targets do improve the laser output at 196 Angstrom, the use of the prepulse technique is shown to be much more important in increasing the laser output. We also discuss the relative effect on the other two important germanium laser lines at 232 and 236 Angstrom.