17–22 May 2026
C.I.D
Europe/Zurich timezone

Implications of Degenerate Mode Mixing in UK XFEL SC Cavities

WEP5088
20 May 2026, 16:00
2h
C.I.D

C.I.D

Deauville, France
Poster Presentation MC5.D03: Calculations of EM fields Theory and Code Developments Poster session

Speaker

Anthony Gilfellon (Cockcroft Institute)

Description

The UK XFEL (United Kingdom X-ray Free Electron
Laser) is a proposed accelerator facility that will use pre-
dominantly superconducting RF structures to accelerate and
manipulate the transiting electron bunches. Deviations from
design longitudinal length of these Niobium RF cavities,
or cells within, caused by errors in manufacturing, fabrica-
tion tolerances, assembly and installation can lead to modes
becoming frequency degenerate. This gives rise to mode
mixing, whereby the component modes combine to form ad-
ditive and subtractive field distributions. Here we look at the
mixing of transverse magnetic (TM) modes and locate prob-
lematic combinations where field strength enhancements
can lead to increased on-axis loss factors and dipole kick
factors, both of which can have adverse effects on the beam
emittance and energy.

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Author

Anthony Gilfellon (Cockcroft Institute)

Co-authors

Mr Alan Wheelhouse (Science and Technology Facilities Council) Bruno Muratori (Science and Technology Facilities Council) Dr Peter Williams (Cockcroft Institute) Prof. Roger Jones (Science and Technology Facilities Council)

Presentation materials

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