EXPERIMENTAL INVESTIGATION OF DOUBLEPASS AMPLIFICATION OF X-RAY LASER IN NEON-LIKE GERMANIUM

The experimental investigations of double-pass amplification of X-ray laser in neon-like germanium were carried out by use of Shengguang laser facilities.In these experiments a molybdenum/silicon multilayer mirror Was used at normal incidence, a flat-field grating spectrograph was used to measure the intensity of lasing lines. We observed the doublepass emission intensity in the neon-like germanium at 23.2 and 23.6 nm that was 5 times larger than that of the single-pass ASE. The enhartcement of double-pass emission could be much larger if the operation period of multilayer mirror was counted in. The damage of multilayer mirror irradiated by laser plasma was measured simultaneously, the lifetime of Mo/Si multilayer mirror was about 440—700ps.In addition, we measured the beam divergence of lasing beam,the resnlts showed that the beam divergence in the vertical direction was about 22 mrad and in the horizontal direction about 12 mrad.