Abstract

By means of a novel double-massive target coupling experimental design, the adverse refraction effect of the x-ray laser beam was reduced, and significant amplification on five lasing lines was observed with wavelengths at 19.6, 23.2, 23.6, 24.7 and 28.6 nm from 3p–3s transitions in Ne-like Ge ions along an elongated plasma column. The fit gain coefficients did not decrease apparently up to 4.0 cm in total target length. Maximum gain-length product values achieved were over 14 for two of the five lasing lines at 23.2 and 23.6 nm. Temporally resolved measurements of x-ray laser spectra, which were made with a soft x-ray streak camera coupled to a flat-field grazing-incidence grating spectrograph, indicated that the duration of the gain was ~0.8 ns comparable to the Gaussian driving laser pulse width, 1 ns (FWHM) in our experiment. The measured divergence and refraction angles of the x-ray laser beam at 23.6 nm are presented. The dimension and position of the gain region were estimated.

© 1991 Optical Society of America