Speaker
Description
We present a concept for a compact soft X-ray Compton source targeting the water-window spectral range (2.3–4.4 nm, 280–540 eV), based on an unconventional combination of three advanced accelerator technologies: laser-wakefield acceleration (LWFA) for top-up injection, a dual-energy accumulator ring with energy recovery, and cryocooled Nb3Sn twin-axis superconducting RF cavities.
The source concept exploits LWFA in the low-energy, high-density regime (n_e ~ 10^19–10^20 cm^-3, a_0 ~ 1–2) to deliver a sub-MeV electron bunch (~0.2 MeV) into a compact storage ring. Electrons are accelerated to ~3 MeV by twin-axis Nb3Sn cavities operating at 4K via cryocooler, then collide with stored photons in a high-finesse optical cavity to produce Compton-scattered X-rays in the water window. After the interaction, the spent beam is decelerated through the same twin-axis cavity structure, recovering most of its energy — the dual-energy accumulator ring architecture thereby supporting both acceleration and deceleration in a single compact cryomodule.
We discuss the physics and engineering of each subsystem: the optimal LWFA injection regime and the interplay between self-injection dynamics, extraction energy, and energy-recovery ratio; the Nb3Sn cavity design with low-beta first cell to accommodate sub-relativistic injection; the estimated Compton photon flux (~10^14–10^16 ph/s) and average power (~30 mW central estimate) in the water window; and the key open questions requiring simulation and experimental validation. The concept represents a qualitatively new point in the design space for compact, lab-scale, coherent-quality X-ray sources, leveraging the maturity of LWFA technology at modest laser energies (35 mJ, 35 fs) to enable a source that would otherwise require a full synchrotron facility.
| Working group | WG4 |
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