Correcting the Magnetic Field Offsets Inside the Undulators of the EuXFEL Using the K-Monochromator

Brinker, Frank; Freund, Wolfgang; Casalbuoni, Sara

Poster

PUBDB-2021-05174

Correcting the Magnetic Field Offsets Inside the Undulators of the EuXFEL Using the K-Monochromator

Brinker, F. (Corresponding author)DESY* ; Casalbuoni, S.XFEL.EU* ; Freund, W.XFEL.EU*

2021

12th International Particle Accelerator Conference, IPAC21, Campinas, Brazil, 24 May 2021 - 28 May 2021

Abstract: Hard X-ray free-electron lasers (XFELs) generate intense coherent X-ray beams by passing electrons through undulators, i.e. very long periodic magnet structures, which extend over hundreds of meters. A crucial condition for the lasing process is the spatial overlap of the electrons with the electromagnetic field. Well-established electron beam-based procedures allow finding a straight trajectory for the electrons defined by the beam position monitors (BPM) between the undulators. A bending of the trajectory in between the BPMs cannot be seen by these methods. A general field offset inside the undulators has the effect that the synchrotron radiation is emitted at a different angle at the beginning and the end of the undulator which can result in a degradation of the FEL-gain especially for very short wavelengths. We report on how the spectral and spatial characteristics of the monochromatized radiation of a single undulator can be used to minimize the field offset in situ with the help of correction coils.

Keyword(s): Accelerator Physics ; MC2: Photon Sources and Electron Accelerators

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