NICKEL-LIKE SOFT-X-RAY LASING AT THE WAVELENGTHS BETWEEN 14 AND 7.9 NM

We report what we believe is the first observation of clear soft-x-ray lasing in Ni-like Ag, Te, La, Ce, and Pr and also in Nd covering the spectral range 14.3-7.9 nm. A curved slab target was irradiated with q uadruple 1.053-mu m laser pulses. The pulse-to-pulse separation for th e first three pulses was 400 ps, and that between the third and the fo urth pulses was 1.6 ns. The pulse duration and irradiance on the targe t were 100 ps and similar to 7 x 10(13) W/cm(2), respectively. For all the targets the most intense lasing was observed at the fourth pump p ulse. (C) 1996 Optical Society of America.