IPAC2018 - List of Authors (Wolff-Fabris, F.)

Paper	Title	Page
WEYGBD2	Status of the Radiation Damage on the European XFEL Undulator Systems	1776
	F. Wolff-Fabris, J. Pflüger XFEL. EU, Schenefeld, Germany F. Hellberg Stockholm University, Stockholm, Sweden F. Schmidt-Föhre DESY, Hamburg, Germany
	The European XFEL GmbH is a new X-ray FEL user facility and started lasing in 2017. Three gap movable SASE Undulator Systems are designed to produce FELs with tunable wavelengths from 0.05 to 5.2nm [,]. A total of 91 5-m long undulator segments based on hybrid NdFeB permanent magnet technology were tuned respecting tight specifications. Radiation damage due to machine operation affects the magnetic properties of the segments and the quality of the SASE process. An array of dosimeters based on Radfets [*] and Gafchromic films monitors the absorbed doses in every undulator segment and each SASE system is equipped with a 12mm gap diagnostic undulator (DU) which is magnetically re-measured during machine maintenance weeks. Doses up to 4 kGy have been observed and magnetic field degradation higher than 3% is measured. These results permit to estimate the effects of radiation damage and life expectancy of the Undulator Systems based on the precise K-parameter determination for beam operation. We will present the results of magnetic re-measurements on the Undulator Systems, the details of the effects of radiation damage and future plans to maximize the beam quality and operation. M. Altarelli et al., Tech. Design Rep. DESY 2006-097, July 2007. E. Schneidmiller et al., Eur. XFEL Tech. Rep. TR-2011-006, Sep. 2011. * F. Schmidt-Föhre et al., IPAC-2018 contribution.
	Slides WEYGBD2 [3.670 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEYGBD2
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THPMF022	Study of Possible Beam Losses After Post-Linac Collimation at European XFEL	4092
	S. Liu, W. Decking DESY, Hamburg, Germany F. Wolff-Fabris XFEL. EU, Schenefeld, Germany
	The European XFEL has been operating with the undulator beam line SASE1 and SASE3 since April 2017 and February 2018, respectively. Despite of the fact that the post-linac collimation has collimated the beam halo to ~20 σ level, relative high radiation doses have been measured especially in the diagnostic undulator (DU) section. In order to find the sources of beam losses after post-linac collimation, BDSIM simulations have been performed. In this paper, we will first present the possible losses generated by the wire scanners upstream of the undulators during a scan. The simulation results will be compared with the measured doses along SASE1 and SASE3 undulators. Based on the simulation results, we will estimate the frequency for wire scanner opera-tions. Besides, the simulations with large extension of beam halo hitting the vacuum chamber aperture transition will also be presented. Finally, other possible radiation dose sources will be discussed. S. Liu et al., in Proc. of FEL 2017, Santa-Fe, USA, Aug. 2017, paper TUP003. ** F. Wolff-Fabris et al.,IPAC-2018 contribution.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF022
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

Paper

Title

Page

Status of the Radiation Damage on the European XFEL Undulator Systems

1776

F. Wolff-Fabris, J. Pflüger
XFEL. EU, Schenefeld, Germany
F. Hellberg
Stockholm University, Stockholm, Sweden
F. Schmidt-Föhre
DESY, Hamburg, Germany

The European XFEL GmbH is a new X-ray FEL user facility and started lasing in 2017. Three gap movable SASE Undulator Systems are designed to produce FELs with tunable wavelengths from 0.05 to 5.2nm [*,**]. A total of 91 5-m long undulator segments based on hybrid NdFeB permanent magnet technology were tuned respecting tight specifications. Radiation damage due to machine operation affects the magnetic properties of the segments and the quality of the SASE process. An array of dosimeters based on Radfets [***] and Gafchromic films monitors the absorbed doses in every undulator segment and each SASE system is equipped with a 12mm gap diagnostic undulator (DU) which is magnetically re-measured during machine maintenance weeks. Doses up to 4 kGy have been observed and magnetic field degradation higher than 3% is measured. These results permit to estimate the effects of radiation damage and life expectancy of the Undulator Systems based on the precise K-parameter determination for beam operation. We will present the results of magnetic re-measurements on the Undulator Systems, the details of the effects of radiation damage and future plans to maximize the beam quality and operation.
* M. Altarelli et al., Tech. Design Rep. DESY 2006-097, July 2007.
** E. Schneidmiller et al., Eur. XFEL Tech. Rep. TR-2011-006, Sep. 2011.
*** F. Schmidt-Föhre et al., IPAC-2018 contribution.

Slides WEYGBD2 [3.670 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEYGBD2

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPMF022

Study of Possible Beam Losses After Post-Linac Collimation at European XFEL

4092

S. Liu, W. Decking
DESY, Hamburg, Germany
F. Wolff-Fabris
XFEL. EU, Schenefeld, Germany

The European XFEL has been operating with the undulator beam line SASE1 and SASE3 since April 2017 and February 2018, respectively. Despite of the fact that the post-linac collimation has collimated the beam halo to ~20 σ level*, relative high radiation doses have been measured especially in the diagnostic undulator (DU) section**. In order to find the sources of beam losses after post-linac collimation, BDSIM simulations have been performed. In this paper, we will first present the possible losses generated by the wire scanners upstream of the undulators during a scan. The simulation results will be compared with the measured doses along SASE1 and SASE3 undulators. Based on the simulation results, we will estimate the frequency for wire scanner opera-tions. Besides, the simulations with large extension of beam halo hitting the vacuum chamber aperture transition will also be presented. Finally, other possible radiation dose sources will be discussed.
* S. Liu et al., in Proc. of FEL 2017, Santa-Fe, USA, Aug. 2017, paper TUP003.
** F. Wolff-Fabris et al.,IPAC-2018 contribution.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF022

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)