FEL2019 - List of Keywords (vacuum)

Paper	Title	Other Keywords	Page
WEP055	Multiphysics Analysis of a CW VHF Gun for European XFEL	gun, cavity, simulation, FEL	456
	G. Shu, Y. Chen, S. Lal, H.J. Qian, H. Shaker, F. Stephan DESY Zeuthen, Zeuthen, Germany
	R&D for a possible future CW mode operation of European XFEL started after the successful commissioning of the pulse mode operation. For the CW electron source upgrade, a fully superconducting CW gun is under experimental development at DESY in Hamburg, and a normal conducting (NC) CW gun is under physics design at the Photo Injector Test facility at DESY in Zeuthen (PITZ) as a backup option. Based on the experience of the LBNL on a 187 MHz gun, the DESY 217 MHz gun increased the cathode gradient and RF power to 28 MV/m and 100 kW, respectively, to further improve the beam brightness. In this paper, the multiphysics analysis investigating the RF, thermal and mechanical properties of the 217 MHz NC CW gun are presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-WEP055
About •	paper received ※ 20 August 2019 paper accepted ※ 28 August 2019 issue date ※ 05 November 2019
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THP068	LCLS-II Extruded Aluminum Undulator Vacuum Chambers — New Approaches to an Improved Aperture Surface Finish	undulator, alignment, electron, FEL	719
	G.E. Wiemerslage, P.K. Den Hartog, J. Qian, M. White ANL, Lemont, Illinois, USA
	Funding: Work at Argonne National Laboratory is supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences under contract # DE-AC02-06CH11357. The Linac Coherent Light Source, (LCLS) the world’s first x-ray free electron laser (FEL) became operational in 2009. The Advanced Photon Source contributed to the original project by designing and building the undulator line. Two slightly different variations of these chambers were required for LCLS-II: one for a soft X-ray (SXR) undulator line, and one for a hard X-ray (HXR) undulator line. Because of the extremely short electron bunch length, a key physics requirement was to achieve the best possible surface finish within the chamber aperture. Improvements to our earlier fabrication methods allowed us to meet the critical surface roughness finish defined by RF impedance requirements. We were able to improve the surface finish from an average of 812 nm rms to 238 nm rms. The average longitudinal surface roughness slope of all chambers was to be less than 20 mrad. We achieved an average longitudinal surface roughness slope of 8.5 mrad with no chamber exceeding 20 mrad. In the end, sixty-four undulator vacuum chambers and alignment systems were delivered to SLAC for the LCLS-II Upgrade project. Here we will report on the process improvements for the fabrication of these chambers.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-THP068
About •	paper received ※ 16 August 2019 paper accepted ※ 27 August 2019 issue date ※ 05 November 2019
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

Paper

Title

Other Keywords

Page

WEP055

Multiphysics Analysis of a CW VHF Gun for European XFEL

gun, cavity, simulation, FEL

456

G. Shu, Y. Chen, S. Lal, H.J. Qian, H. Shaker, F. Stephan
DESY Zeuthen, Zeuthen, Germany

R&D for a possible future CW mode operation of European XFEL started after the successful commissioning of the pulse mode operation. For the CW electron source upgrade, a fully superconducting CW gun is under experimental development at DESY in Hamburg, and a normal conducting (NC) CW gun is under physics design at the Photo Injector Test facility at DESY in Zeuthen (PITZ) as a backup option. Based on the experience of the LBNL on a 187 MHz gun, the DESY 217 MHz gun increased the cathode gradient and RF power to 28 MV/m and 100 kW, respectively, to further improve the beam brightness. In this paper, the multiphysics analysis investigating the RF, thermal and mechanical properties of the 217 MHz NC CW gun are presented.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-WEP055

About •

paper received ※ 20 August 2019 paper accepted ※ 28 August 2019 issue date ※ 05 November 2019

Export •

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

THP068

LCLS-II Extruded Aluminum Undulator Vacuum Chambers — New Approaches to an Improved Aperture Surface Finish

undulator, alignment, electron, FEL

719

G.E. Wiemerslage, P.K. Den Hartog, J. Qian, M. White
ANL, Lemont, Illinois, USA

Funding: Work at Argonne National Laboratory is supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences under contract # DE-AC02-06CH11357.
The Linac Coherent Light Source, (LCLS) the world’s first x-ray free electron laser (FEL) became operational in 2009. The Advanced Photon Source contributed to the original project by designing and building the undulator line. Two slightly different variations of these chambers were required for LCLS-II: one for a soft X-ray (SXR) undulator line, and one for a hard X-ray (HXR) undulator line. Because of the extremely short electron bunch length, a key physics requirement was to achieve the best possible surface finish within the chamber aperture. Improvements to our earlier fabrication methods allowed us to meet the critical surface roughness finish defined by RF impedance requirements. We were able to improve the surface finish from an average of 812 nm rms to 238 nm rms. The average longitudinal surface roughness slope of all chambers was to be less than 20 mrad. We achieved an average longitudinal surface roughness slope of 8.5 mrad with no chamber exceeding 20 mrad. In the end, sixty-four undulator vacuum chambers and alignment systems were delivered to SLAC for the LCLS-II Upgrade project. Here we will report on the process improvements for the fabrication of these chambers.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-THP068

About •

paper received ※ 16 August 2019 paper accepted ※ 27 August 2019 issue date ※ 05 November 2019

Export •

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