ABSTRACT
Intense 3p - 3s, J = 0 - 1 soft-x-ray lasing at 28.5 nm in neon-like chromium has been observed experimentally using a compact Nd:glass laser as the driver. 2.4-cm long chromium slab targets were irradiated with up to 100-J/500-ps pulses at the fundamental wavelength of 1.054 μm. The prepulse technique was applied using a defined prepulse 5 ns before the main pulse and with a prepulse-to-main pulse energy ratio of 0.7%. It is demonstrated that a pump energy of 82 J, corresponding to a pump irradiance of ~9 TW/cm2 is sufficient to observe soft-x-ray lasing at 28.5 nm. At a drive laser energy of ~90 J a gain coefficient of (2.2±0.5) cm-1 was measured. The one-dimensional space-resolved measurements show that the 28.5-nm laser line is emitted in a 60-μm wide (FWHM) plasma region.
