Progress in the development of table-top discharge pumped soft x-ray lasers

The demonstration of large soft x-ray amplification In a discharge-created plasma has opened a new path to the development of compact and practical soft x-ray lasers. We review our progress in the development and study of these ultrashort wavelength lasers. The field has advanced from the first observation of large amplification in a discharge-created plasma in Ne-like Ar [J.J. Rocca, V.N. Shlyaptsev, F.G. Tomasel, O.D. Cortazar, D. Hartshorn, and J.L.A. Chilla, Phys. Rev. Lett. 73. 2192 (1994)]. to the demonstration of an extremely compact saturated laser at 46.9 run. In this paper wt: give an overview of these and other selected results. They include the: observation of large amplification (gain-length product of 7.5) in Ne-like S at 60.8 nm in material ablated from a solid target by a discharge, and preliminary results of the search for gain at a shorter wavelength in Ne-like Ca. A recent study of the spatial coherence of the capillary discharge 46.9 nm Ne-like Ar laser. which provides the first experimental measurement of a monotonic increase of the spatial coherence with length in a soft x-ray amplifier, is also summarized.