On the theory of multi-target coded sources for high-energy, high-resolution, and high-brightness x-ray radiography.

Abstract

X-ray radiography is a ubiquitous diagnostic technique in high energy density (HED) physics, with point projection backlighting commonly used for characterizing static and dynamic objects at high spatial and temporal resolutions. These are typically constrained in attainable resolution by their decrease in brightness, which is a limiting factor for high-Z HED experiments, such as double-shell implosions at the National Ignition Facility (NIF) requiring MeV-scale bremsstrahlung sources at high (<50μm) resolution. Coded source imaging is a technique using multiple point-projection sources to produce multiple overlapping radiographs, which are then decoded as a function of the source positions in a process akin to coded aperture imaging. Here, we discuss a new approach to coded source generation using multiple individual small-diameter wire targets within the footprint of a defocused large-scale a0 ≃ 1 laser to produce an MeV-scale high-resolution bright combined source for x-ray radiography. We outline optimal source designs with NIF-Advanced Radiography Capability as the case study, highlight the need for iterative reconstruction decoding, and discuss the research required to demonstrate a robust physical proof-of-concept.