ABSTRACT
Amplification of Li-like Al soft x-ray transitions was: observed in plasmas produced by irradiation of a pulse-train YAG laser onto an Al slab target. The input laser energy was 1.5-2 J. The gain coefficient measured for the 15.47 nm line was 3.2 cm-1 and the duration of gain was longer than i ns. hxperiments of double-pass amplification were also perlormed hy using a flat Mo/Si multilayer mirror. We observed that the 15.47 nm line intensity has been amplified up to 3 times that of the single-pass case.
