Because the maximum achievable photon energy for compact Compton-scattering x-ray sources is currently limited by the maximum permissible field gradient of conventional electron accelerators, the radio-frequency (RF)-driven x-ray source at Livermore National Laboratory (LLNL; Livermore, CA), for example, produces 478 keV x-ray beams with 12% spectral bandwidth, 16 ps temporal duration with a flux of 1 × 10~5 photons per shot, for a 1.5 × 10~(15) photons/s-mm~2-mrad~2 peak brilliance (per 0.1% bandwidth). But by instead using a compact, all-optical laser-wakefield accelerator (LWFA), researchers at the University of Nebraska-Lincoln (Lincoln, NE) can produce quasi-monoenergetic (<50% full width half maximum or FWHM), tunable x-rays that are a thousand times brighter with 10 times more photons per shot than conventional RF-driven sources.
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