Enhanced Fluorescence from X-Ray Line Coincidence Pumping

Many resonant photo-pumped X-ray laser schemes that use a strong pump line such as Ly-alpha or He-alpha to populate the upper laser state of a separate lasing material have been proposed over the last four decades but none have been demonstrated. As a first step to creating a photo-pumped X-ray laser we have decided to reinvestigate some of these schemes at the Orion laser facility with the goal to show enhanced fluorescence. In particular we look at using the Ly-alpha or He-alpha K lines to pump the 1s-3p and 4p transitions in H-like Cl and see fluorescence on the 4f-3d line at 65 angstrom and the 3d-2p line at 23 angstrom. Preliminary experiments are presented that show a modest enhancement. As an alternative we also look at enhancing the 2p-2s line in Ne-like Ge at 65 angstrom using the Ly-alpha Mg line to photo-pump the 2s-3p line of Ne-like Ge. Calculations are presented that suggest modest enhancements of 2.5.