Development of a Laser-Based Stable K-alpha X-ray Source using Fluorescence

Several oft-used measurement techniques in high energy-density physics and inertial confinement fusion experiments, including radiography, diffraction, and X-ray Thomson scattering, require a high energy, narrowband x-ray source, preferably from an isolated line emission that is stable throughout the duration of an experiment (of order nanosecond). We investigate and develop a concept comprising a laser-heated target and nearby witness foil, such that the former photopumps the latter, generating fluoresced monochromatic K-alpha for >=1 nanosecond. Two target designs were tested at the OMEGA laser facility: Ge-lined tubes with either a side-mounted or end-mounted Zn foil. The data collected include both the Ge and Zn K-shell X-ray emission spectrum for evaluation of laser to x-ray conversion efficiency as well as backscattered light to evaluate laser coupling to the target. We will discuss the performance of the source platform across minor modifications to target design parameters as well as laser intensity, duration and pulse shapes.