X-ray laser research at advanced photon research center of JAERI, Kansai

We have observed lasing on Ne-like 3s-3p line from titanium (32.4nm), Ni-like 4p-4d line from silver (13.9nm) and tin (11.9nm) with the transient collisional excitation (TCE) scheme that uses combinations of a long pre-pulse (similar tons) and a short main pulse (similar tops) or a short pre-pulse (similar tops) and a short main pulse (similar tops). A gain coefficient of 24cm(-1) have been measured for plasma length up to 4mm with silver slab targets and 14cm(-1) up to 6mm with tin slab targets. We have installed a step mirror in the focusing system to generate traveling wave on the target. The traveling speed on the target is measured to be 3.08cm/s; and very close to the traveling speed of light. The traveling wave system improves the gain coefficient to 35cm(-1) from 24cm(-1) for Ni-like Ag and to 30cm(-1) from 14cm(-1) for Ni-like Sn. The strong gain saturation has been observed for the Ni-like Ag and Ni-like Sn. The output energy o the N-like Sn x-ray laser is 20muJ. Spatial beam profiles of propagating x-ray lasers through gain plasma have been measured and are indicating localization of very high gain area and x-ray laser refraction.