Speaker
Description
RadiaBeam Technologies has commissioned, characterized, and begun demonstrating applications of a highly tunable inverse Compton scattering (ICS) X-ray source based on a 100 MeV-class C-band electron linac. The photoinjector features a hybrid structure achieving sub-picosecond bunch compression within a compact footprint, suitable for a containerized final size. Two C-band linacs with adjustable RF power accelerate a 250 pC beam to between 30–95 MeV, with energy tunability achieved by adjusting the RF power balance between the two accelerating sections. Energy spreads of less than 0.5% rms were measured using a 45° dipole across the full energy range. Sub-micron normalized emittance was measured at 94 MeV via quadrupole scan, in good agreement with digital twin simulations and initial design work. Beam stability was studied as a function of the low-level RF subsystem, and active low-frequency fluctuation compensation was introduced into the control system.
The interaction laser is a picosecond 1030 nm pulse delivering up to 18 mJ to the interaction point, where both laser and electron beam are focused to spot sizes of σ < 30 μm. The nearly head-on electron-photon collision (3° crossing angle) produces X-rays with peak energies tunable from 30 keV to 100 keV, with up to 10⁵ photons per shot. X-ray photon count, beam divergence, spatial-spectral coupling, and local bandwidth have been measured across the tunability spectrum, with results generally agreeing with theoretical predictions and simulations.
Applications of the ICS source have begun to be explored, including successful demonstrations of K-edge imaging using elemental foils spanning from Ag (Z=47, K-edge at 25.5 keV) to Pb (Z=82, K-edge at 88.0 keV), showing clear material discrimination and spatial absorption contrast only achievable with high-quality, sub-picosecond electron bunches. Active efforts are also underway to focus the X-ray beam to micron-scale spot sizes for material and device inspection. Broader applications in fields such as medical imaging are being pursued.
| Working group | WG6 |
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