Abstract

The development of table-top soft-x-ray lasers driven at pump energies well below the kilojoule level has become a primary issue in x-ray laser research. Lasing has been observed on the collisionally-pumped 3p→3s transitions in neon-like ions at wavelengths from 53 to 18 nm. Drive laser energies were reduced to below -200 J when the prepulse technique was applied, in which a low-energy pulse irradiates the target a few nanoseconds before the main pulse [1,2]. In this work we report on the experimental demonstration of 3p→3s (J = 0 - 1) soft x-ray lasing at 28.5 nm in neon-like chromium using a table-top drive laser and the prepulse technique. With a 0.7% prepulse 5 ns before the main pulse, lasing at 28.5 nm was observed at a pump energy of 90 J, corresponding to an irradiance of ~10 TW/cm². The experiments were performed using a Nd:glass laser system capable of delivering up to 120 J at 1.054 µm with a pulse duration of 500 ps. The line-focused laser irradiated 2.4-cm long polished chromium slab targets. The principal diagnostics used was a time-integrating, space-resolving spectrometer having a spatial resolution of ~50 µm and a spectral resolution of 0.2 nm

© 1996 IEEE