Femtosecond-Scale MeV-UED Beamline Using a Stand-Alone Multi-Cell RF Photogun

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Hauptverfasser: Lucas, Thomas Geoffrey, Craievich, Paolo, Alesini, David, Beard, Carl, Braun, Hans-H., Dietrich, Alexander, Geng, Zheqiao, Ischebeck, Rasmus, Prat, Eduard, Seidel, Mike, Sydlo, Cezary, Trisorio, Alexandre, Vicario, Carlo, Zennaro, Riccardo
Format: Preprint
Veröffentlicht: 2025
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author Lucas, Thomas Geoffrey
Craievich, Paolo
Alesini, David
Beard, Carl
Braun, Hans-H.
Dietrich, Alexander
Geng, Zheqiao
Ischebeck, Rasmus
Prat, Eduard
Seidel, Mike
Sydlo, Cezary
Trisorio, Alexandre
Vicario, Carlo
Zennaro, Riccardo
author_facet Lucas, Thomas Geoffrey
Craievich, Paolo
Alesini, David
Beard, Carl
Braun, Hans-H.
Dietrich, Alexander
Geng, Zheqiao
Ischebeck, Rasmus
Prat, Eduard
Seidel, Mike
Sydlo, Cezary
Trisorio, Alexandre
Vicario, Carlo
Zennaro, Riccardo
contents The temporal resolution of MeV ultrafast electron diffraction (UED) is fundamentally constrained by the electron bunch length at the sample, motivating the development of new electron sources capable of producing femtosecond scale bunches. In this work, we propose a multicell RF photogun that has a tailored phase velocity profile to generate 5 to 15 fs rms MeV electron bunches directly from the electron gun, eliminating the need for downstream compression. This approach achieves comparable performance to conventional one and a half cell photoguns with downstream compression, while reducing system size, complexity, and power requirements. We examine two implementations: a standing wave (SW) and a travelling wave (TW) design. The TW variant demonstrates over an order of magnitude lower power dissipation than typical SW structures, enabling potential kHz operation. When paired with SwissFEL style C band RF sources, which offer high amplitude and phase stability, the TW photogun is projected to deliver a temporal resolution of 26 fs rms.
format Preprint
id arxiv_https___arxiv_org_abs_2508_09357
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Femtosecond-Scale MeV-UED Beamline Using a Stand-Alone Multi-Cell RF Photogun
Lucas, Thomas Geoffrey
Craievich, Paolo
Alesini, David
Beard, Carl
Braun, Hans-H.
Dietrich, Alexander
Geng, Zheqiao
Ischebeck, Rasmus
Prat, Eduard
Seidel, Mike
Sydlo, Cezary
Trisorio, Alexandre
Vicario, Carlo
Zennaro, Riccardo
Accelerator Physics
The temporal resolution of MeV ultrafast electron diffraction (UED) is fundamentally constrained by the electron bunch length at the sample, motivating the development of new electron sources capable of producing femtosecond scale bunches. In this work, we propose a multicell RF photogun that has a tailored phase velocity profile to generate 5 to 15 fs rms MeV electron bunches directly from the electron gun, eliminating the need for downstream compression. This approach achieves comparable performance to conventional one and a half cell photoguns with downstream compression, while reducing system size, complexity, and power requirements. We examine two implementations: a standing wave (SW) and a travelling wave (TW) design. The TW variant demonstrates over an order of magnitude lower power dissipation than typical SW structures, enabling potential kHz operation. When paired with SwissFEL style C band RF sources, which offer high amplitude and phase stability, the TW photogun is projected to deliver a temporal resolution of 26 fs rms.
title Femtosecond-Scale MeV-UED Beamline Using a Stand-Alone Multi-Cell RF Photogun
topic Accelerator Physics
url https://arxiv.org/abs/2508.09357