An MeV X-ray source from Laser Wakefield Acceleration based betatron radiation

Laser-plasma based X-ray sources are of interest for High Energy Density Science applications, such as imaging an Inertial Confinement Fusion implosion to observe the role of instabilities (Rayleigh-Taylor instability, etc.). The desired X-ray source has a high spatial and temporal resolution, and a spectrum up to 100s of keV to image inside the gold hohlraum. A betatron X-ray source from Laser-Wakefield Acceleration (LWFA) has enhanced temporal resolution when compared to currently existing X-ray backlighters, because the temporal resolution is synchronized with the laser pulse, providing fs resolution when driven with a fs-scale pulse. Typically, betatron X-ray sources provide a spatial resolution of sub-10 microns, depending on the laser plasma parameters. This work will benchmark the spectral range and spatial resolution of a betatron X-ray source from plasma waveguide enhanced LWFA, which have never been measured before.

We will present results from an experiment in August 2025 at the ELBA end station at ELI Beamlines with the HAPLS laser (800 nm, 30 fs, 15 J, .2 Hz), and characterize the resulting flux, critical energy, and source size of the betatron X-rays. This will also provide greater experimental knowledge of processes undergone in the wake in this novel injection scheme such as the electron beam trajectories, which are measured through betatron X-ray source size. In previous experiments, low flux and instability from shot-to-shot were drawbacks when applying betatron X-rays to applications, compared to current methods (X-ray tubes, Synchrotron sources). By examining the impact of this novel injection mechanism on LWFA X-ray source generation, we will better understand how a careful tailoring of electron beam parameters in a LWF can dictate X-ray source parameters and therefore suitability for specific applications.