Beam-Driven Transverse Deflecting Structure for Femtosecond Electron-Beam Diagnostics
Abstract
High-resolution longitudinal phase-space (LPS) diagnostics are essential for X-ray free-electron lasers and advanced accelerators. Conventional radio-frequency transverse deflecting structures (TDSs) provide direct femtosecond-scale LPS measurements, but their substantial RF-power and infrastructure requirements strongly limit their deployment at multi-GeV beam energies. Here, we propose a beam-driven transverse deflecting structure in which a leading driver bunch, separated by one RF bucket from a trailing witness bunch under study, excites long-lived wakefields in a resonant cavity array. By placing the witness bunch near a zero crossing of the wakefield, the bunch experiences an approximately linear time-dependent transverse kick. Electromagnetic simulations of the resonant structure, combined with start-to-end beam-dynamics simulations based on European XFEL parameters at a final beam energy of 14 GeV, demonstrate a temporal resolution of fs for a 500 pC driver bunch, with a clear scaling toward the sub-femtosecond regime at higher charge.
Cite
@article{arxiv.2605.13752,
title = {Beam-Driven Transverse Deflecting Structure for Femtosecond Electron-Beam Diagnostics},
author = {S. Tomin and D. Bazyl and W. Decking and I. Zagorodnov},
journal= {arXiv preprint arXiv:2605.13752},
year = {2026}
}