We report the demonstration of laser amplification at 52.9 nm in Ne-like Cl with a compact capillary discharge. Laser output pulses with energies of as much as 10 muJ have been obtained. The beam divergence was approximately 4 mrad. This new 23.4-eV tabletop laser is of particular interest for applications that require high peak fluxes of photons with energy slightly below the He photoionization threshold.

We report the generation of plasma columns in gas-filled capillary channels using discharge excitation powers that exceed those of previous studies by one to two orders of magnitude. Current pulses up to 200 kA and 10-90 % rise time of ϳ10 ns ͑current increase rate ϳ1.5ϫ1013 A/s͒ were utilized to excite plasmas in 3.3 and 4 mm diameter channels. Time resolved soft-x-ray spectra and pinhole images of the plasma were obtained. The experimental data and its comparison with model computations suggest that dense argon plasma columns 300 m in diameter with electron temperatures Ͼ250 eV have been obtained. These characteristics make these plasmas of interest for extending discharge-pumped lasers to shorter wavelengths.

Abstract.For many years, researchers have envisioned the development of compact high repetition rate tabletop soft X-ray lasers that could be routinely used in application in numerous disciplines. With demonstrated average powers of several mW and mJ-level pulse energy at 46.9 nm, capillary discharge-pumped lasers are the first compact lasers to reach this goal. In this paper we summarize the development status of high repetition rate tabletop soft X-ray lasers based on capillary discharge excitation, and give examples of their successful use in several applications. Results of the use of a capillary discharge pumped 46.9 nm laser in dense plasma interferometry, soft X-ray reflectometry for the determination of optical constants, and laser ablation are described. The observation of lasing at 53 nm line in Ne-like Cl with output pulse energy up to 10 µJ is also reported. © 2000 Académie des sciences/Éditions scientifiques et médicales Elsevier SAS tabletop soft X-ray lasers Vers de nouvelles longueurs d'onde et applications pour les lasers X-UV compacts à décharge capillaire Résumé. Depuis de nombreuse années, les chercheurs prévoient le développement de laser X-UV compacts, dits « de table », qui pourraient être utilisés en routine pour les applications à des disciplines variées. Avec des puissances moyennes mesurées de plusieurs

.\b!.tract. For many years researchers have envisioned the development of compact high repetition rate tabletop soft x-ray la;er, that could be routmcly used in application in numerous disciplines. With demonstrated average powers of several mW and milliJouk-ln cl pulse encq;y at 46.9nm, the Ne-likc Ar capillary discharge-pumped laser is the first compact laser to reach thrs goal. ln tillS paper we summan~e the development status of high repetition rate tabletop soft x-ray lasers based on capillary drscharge excrtation, and grvc examples of their successful use in several applications. Results of the use of a caprllary discharge pumped 46.9nm laser m dense plasma interferometry, soft x-ray reflcctometry for the determmation of optical constants. characterization of diffraction gratings, laser ablation of materials, and plasma generation are described. The ohscT,·atron of laSing at _'i2.9runline rn Ne-like C'l with output pulse energy up to 10 ).lJ is also reported.

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