Geant4 Simulations of Bremsstrahlung X-ray Sources for Terawatt Laser Systems

Terawatt-class laser systems can be used to produce compact, high-energy x-ray sources with

high temporal and spatial resolution when compared to traditional accelerator-based sources.

These systems hold significant potential as future secondary radiation sources relevant to

multiple disciplines. Of particular interest to this work, are bremsstrahlung sources utilizing

relativistic electrons to produce x-rays in the ~100keV regime. In this configuration, a narrow

beam of relativistic electrons is generated through the laser wakefield acceleration [1] process

that is incident on to a converter foil where the electrons lose energy and emit x-rays. Geant4

simulations have been conducted to assess different potential x-ray spectra for a variety of

converter foil materials and thicknesses using a realistic electron spectrum (~1-5 MeV) produced

on the GALADRIEL laser facility [2] at General Atomics. Simulated x-ray spectra will be shown

and discussed in the context of future experiments to characterize bremsstrahlung sources at

GALADRIEL. These results will be useful for optimizing bremsstrahlung sources for use in

high-resolution imaging and hardened electronics testing.

Funding Acknowledgements: This research is funded by internal research and development

funds at General Atomics, the National Science Foundation under Grant No. PHY-2206777, and

the Air Force Office of Scientific Research under Grant No. FA9550-24-1-0053.