OBSERVATION OF HIGH TRANSIENT GAIN IN THE GERMANIUM X-RAY LASER AT 19.6 NM

The transient-excitation pumping scheme, in which a picosecond duratio n pulse rapidly heats the plasma preformed by a low-intensity nanoseco nd pulse, was used to pump the Ne-like germanium, J = 0-1 transition a t 19.6 nm. A small-signal gain coefficient of 30 cm(-1) was measured f or targets less than or equal to 5 mm long. (C) 1998 Optical Society o f America.