FZP-based High-Resolution Imprint Radiography Platform

In laser-direct-drive implosions, Rayleigh-Taylor (RT) amplification of laser imprint modes increases the in-flight shell thickness degrading the performance of low-adiabat designs. The development of laser-driven imprint mitigation strategies relies on direct measurements of the imprint-induced density modulations in focused experiments through x-ray radiography. Typical radiographic measurements utilize a broadband backlighter with ~100's of eV of bandwidth and imaging pinholes to achieve 5-10 µm spatial resolution. Since most of the imprint spectrum is beyond the resolution of the imaging system, only the low mode density modulations amplified by the RT instability are able to be measured. By deploying a Fresnel zone plate to image the Aluminum H-alpha x-ray line as a monochromatic backlighter, near 1 µm spatial resolution can be achieved allowing for the full spatial spectrum to be measured through RT amplification, and possibly earlier when the imprint modes have not been altered by RT growth. This will help elucidate details of the imprinting and guide in the development of more efficient mitigation strategies. This material is based upon work supported by the Department of Energy [National Nuclear Security Administration] University of Rochester "National Inertial Confinement Fusion Program" under Award Number DE-NA0004144.