Abstract

The development of practical "table-top" sources of soft x-ray laser radiation will have a very important impact in many disciplines of science and technology. We summarize the successful development of saturated table-top soft x-ray lasers directly excited by fast discharges. In this excitation scheme amplification occurs in a hot and dense needle-shaped plasma column generated by a fast compressional discharge in a capillary channel [1,2]. The observation of large soft x-ray amplification in Ne-like Ar at 46.9nm in a capillary discharge created plasma [1] and the subsequent demonstration of a saturated table-top laser in this transition [2] have shattered the earlier perception that discharge-created plasmas are insufficiently uniform for soft x-ray lasing, opening a new path for the development of compact and practical soft x-ray lasers. In this talk we review the progress in the development of these ultrashort wavelength lasers, that includes the demonstration of an extremely compact saturated 46.9nm Ne-like Ar laser, and the recent observation of lasing in Ne-like S at 60.8nm in material ablated from a solid target by a discharge [3]. We will also discuss results of the detailed characterization of the capillary discharge pumped Ne-like Ar laser, that includes two-dimensional near-field and far field images of the laser output and the measurement of its spatial coherence as a function of plasma column length[4]. We have observed for the first time a monotonic increase of the spatial coherence with amplifier length in a soft x-ray amplifier, in agreement with the results of wave-optics model computations.

© 1998 IEEE