Increasing the gain-length product of x-ray lasers

Abstract We describe the efforts that are pursued in our laboratory in order to increase the gain-length product of X-ray lasers above 10 and to possibly reach saturation. We report on the recent achievement of a GL of 6 at 206.5 A in a 2 cm long sulfur plasma. We discuss the results of 1D- and 2D-modelling studies that give indications for future experiments on Li-like aluminium. Finally we present the measurement of a GL of 5 at 232 and 236 A in Ne-like germanium.