X-ray backlighter development for high energy density experiments on NIF*

Bright, high-energy backlighters are an essential diagnostic tool for experiments on high energy density facilities. Laser driven 5-12 keV thermal He$_\alpha$ x-ray sources are widely used in ICF/HED experiments, and higher energy 17-50 keV cold K$_\alpha$ sources have been developed using short pulse, petawatt lasers. For many x-ray imaging applications, both source brightness and spatial resolution are crucial. In order to optimize these characteristics, we compared the x-ray emission from Ag foils irradiated with 1 $\mu$m and $^1$/$_3$ $\mu$m wavelength laser light. We find that single-sided laser illumination of $\mu$-flag foils tamped with diamond on the back side improves the spatial resolution in a point-projection imaging configuration. Monte Carlo methods are adopted to fully understand the diagnostic spatial resolution using x-ray knife-edge data. Experimental results from Omega and NIF are shown where 1D and 2D simulations have been employed to optimize brightness and spatial resolution.