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The absolute yields of multiply charged ions of the noble gases argon, krypton, and xenon as functions of laser intensity at ^=586 nm is reported. The measurements were performed with a well characterized picosecond dye laser in the range 10 13 to 4xl0 14 W/cm 2 . Charge states up to Ar +4 , Kr +5 , and Xe +6 were observed at the highest intensities. An extension of the Keldysh-Reiss-Faisal theory which accounts for the Coulomb field of the residual ion is presented and found to be in good agreement with the experimental results with no adjustable parameters.

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We are developing a long-duration K-α x-ray source at the Omega laser facility. Such sources are important for x-ray scattering measurements at small scattering angles where high spectral resolution is required. To date, He-α x-ray sources are the most common probes in scattering experiments, using ns-class lasers to heat foils to keV temperatures, resulting in K-shell emission from He-like charge states. The He-α spectrum can be broadened by emission from multiple charge states and lines (e.g., He-like, Li-like, Be-like). Here, we combine the long duration of He-α sources with the narrow spectral bandwidth of cold K-α emission. A Ge foil is irradiated by the Omega laser, producing principally Ge He-α emission, which pumps Zn K-α emission at 8.6 keV from a nearby Zn layer. Using this technique, we demonstrate a long-duration Zn K-α source suitable for scattering measurements. Our experimental results show a 60% reduction in spectral bandwidth compared to a standard Zn He-α source, significantly improving the measurement precision of scattering experiments with small inelastic shifts.