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arXiv · 2605.13752

Beam-Driven Transverse Deflecting Structure for Femtosecond Electron-Beam Diagnostics

S. Tomin·D. Bazyl·W. Decking·I. Zagorodnov
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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 $\sim 1.6$ fs for a 500 pC driver bunch, with a clear scaling toward the sub-femtosecond regime at higher charge.

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S. Tomin, D. Bazyl, W. Decking, I. Zagorodnov. 2026-05-13. Beam-Driven Transverse Deflecting Structure for Femtosecond Electron-Beam Diagnostics. https://arxiv.org/abs/2605.13752

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