Multi-keV X-ray Yields from High-Z Targets Fielded at the OMEGA Laser and the National Ignition Facility*

We report on measurements and modeling of fluxes from X-ray source targets recently shot at the National Ignition Facility (NIF) and at the Omega laser. The targets were thin-walled pipes filled with mixtures of Xe and Ar gas at pressures of 1 to 1.5 atmospheres. The targets were irradiated with 3$\omega $ laser light, 20 kJ in 1 ns at Omega and 350 kJ in 5 ns at NIF. The emitted X-ray flux was monitored with multiple channels of X-ray-diode based DANTE instruments, and imaged with gated X-ray detectors. We compare predicted X-ray yields to measure yields. The current modeling appears to under-predict the yield of gas mixtures containing Ar. We also report on design and modeling of Fe foam-filled and stainless steel-lined targets.