Demonstration of a high average power tabletop soft X-ray laser

We report the first demonstration of a high average power tabletop soft x-ray laser. An average laser output power of approximate to 1 mW (>2 X 10(14) photons/s) was generated at 46.9 nm in Ne-Like Ar using a very compact tabletop discharge. The spatially coherent average power emitted by this 26.5 eV laser is comparable to that generated at this photon energy in a similar bandwidth (Delta lambda/lambda = 10(-4)) by a third-generation synchrotron beam line. Lasing was obtained at a repetition rate of 7 Hz with an average output energy of 135 mu J/pulse by exciting a plasma column in a ceramic capillary with a fast current pulse. This very compact high-repetition-rate laser source makes intense short-wavelength coherent radiation accessible to a wide variety of new applications.