Phase-contrast imaging with laser-plasma-accelerator betatron sources

Abstract

Laser-plasma accelerators (LPAs) are known to intrinsically produce broad-bandwidth X-rays through the transverse motion of the accelerated electrons in the plasma wakefield. Due to the compact dimensions of the wakefield structure, this motion results in betatron radiation emission from a small point-like source (of order 1 µm in transverse size). Such a small source size enables high spatial resolution single-shot phase-contrast imaging, even for broad photon-energy spreads, simply by propagating the X-rays through a sample and onto a two-dimensional detector. In this manuscript we study, through simulations, the possibility to extend the resolution to the submicron regime. We find that the optimum geometry for <15 keV photons demands short (few-mm) drifts from source-to-sample, a photon flux of order 10 9 photons/shot, and the necessity to take the longitudinal source dimension into consideration. The presented framework behind the simulations will guide future betatron source development. The same expressions are also valid for other point-like LPA radiation sources such as Thomsonand Compton-scattered radiation.