SRF2019 - List of Authors (Walker, N.)

Paper	Title	Page
MOFAA2	Operation of the European XFEL Towards the Maximum Energy	9
	M. Omet, V. Ayvazyan, J. Branlard, S. Choroba, W. Decking, V.V. Katalev, D. Kostin, L. Lilje, P. Morozov, Y. Nachtigal, H. Schlarb, V. Vogel, N. Walker, B. Yildirim DESY, Hamburg, Germany
	After the initial commissioning of the available 25 radio frequency (RF) stations of the European XFEL (RF gun, A1, AH1 and stations A2 through A23) a maximum electron beam energy of 14.5 GeV was achieved, 3 GeV short of the design energy of 17.5 GeV. In order to tackle this problem, the Maximum Gradient Task Force (MGTF) was formed. In the scope of the work of the MGTF, RF stations A6 through A25 (linac L3) were systematically investigated and voltage-limiting factors of the SRF accelerating modules and their RF distribution system were identified and improved. As a result, the design electron beam energy was exceeded at 17.6 GeV on the 18.7.2018. Beside this an overview over the regular RF operation at the European XFEL is given.
	Slides MOFAA2 [5.695 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-MOFAA2
About •	paper received ※ 21 June 2019 paper accepted ※ 30 June 2019 issue date ※ 14 August 2019
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOP023	Nitrogen Infusion Sample R&D at DESY	77
SUSP002	use link to see paper's listing under its alternate paper code
	C. Bate, A. Dangwal Pandey, A. Ermakov, B. Foster, T.F. Keller, D. Reschke, J. Schaffran, S. Sievers, N. Walker, H. Weise, M. Wenskat DESY, Hamburg, Germany W. Hillert University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany G.D.L. Semione, V. Vonk DESY Nanolab, FS-NL, Hamburg, Germany A. Stierle University of Hamburg, Hamburg, Germany
	The European XFEL continuous wave upgrade requires cavities with reduced surface resistance (high Q-values) for high duty cycle while maintaining high accelerating gradient for short-pulse operation. A possible way to meet the requirements is the so-called nitrogen infusion procedure. However, a fundamental understanding and a theoretical model of this method are still missing. The approach shown here is based on sample R&D, with the goal to identify key parameters of the process and establish a stable, reproducible recipe. To understand the underlying processes of the surface evolution, which gives improved cavity performance, advanced surface analysis techniques (e.g. SEM/EDX, TEM, XPS, TOF-SIMS) are utilized. Additionally, a small furnace just for samples was set up to change and explore the parameter space of the infusion recipe. Results of these analyses, their implications for the cavity R&D and next steps are presented.
	Poster MOP023 [3.759 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-MOP023
About •	paper received ※ 23 June 2019 paper accepted ※ 30 June 2019 issue date ※ 14 August 2019
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

Paper

Title

Page

Operation of the European XFEL Towards the Maximum Energy

9

M. Omet, V. Ayvazyan, J. Branlard, S. Choroba, W. Decking, V.V. Katalev, D. Kostin, L. Lilje, P. Morozov, Y. Nachtigal, H. Schlarb, V. Vogel, N. Walker, B. Yildirim
DESY, Hamburg, Germany

After the initial commissioning of the available 25 radio frequency (RF) stations of the European XFEL (RF gun, A1, AH1 and stations A2 through A23) a maximum electron beam energy of 14.5 GeV was achieved, 3 GeV short of the design energy of 17.5 GeV. In order to tackle this problem, the Maximum Gradient Task Force (MGTF) was formed. In the scope of the work of the MGTF, RF stations A6 through A25 (linac L3) were systematically investigated and voltage-limiting factors of the SRF accelerating modules and their RF distribution system were identified and improved. As a result, the design electron beam energy was exceeded at 17.6 GeV on the 18.7.2018. Beside this an overview over the regular RF operation at the European XFEL is given.

Slides MOFAA2 [5.695 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-MOFAA2

About •

paper received ※ 21 June 2019 paper accepted ※ 30 June 2019 issue date ※ 14 August 2019

Export •

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

MOP023

Nitrogen Infusion Sample R&D at DESY

77

SUSP002

use link to see paper's listing under its alternate paper code

C. Bate, A. Dangwal Pandey, A. Ermakov, B. Foster, T.F. Keller, D. Reschke, J. Schaffran, S. Sievers, N. Walker, H. Weise, M. Wenskat
DESY, Hamburg, Germany
W. Hillert
University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany
G.D.L. Semione, V. Vonk
DESY Nanolab, FS-NL, Hamburg, Germany
A. Stierle
University of Hamburg, Hamburg, Germany

The European XFEL continuous wave upgrade requires cavities with reduced surface resistance (high Q-values) for high duty cycle while maintaining high accelerating gradient for short-pulse operation. A possible way to meet the requirements is the so-called nitrogen infusion procedure. However, a fundamental understanding and a theoretical model of this method are still missing. The approach shown here is based on sample R&D, with the goal to identify key parameters of the process and establish a stable, reproducible recipe. To understand the underlying processes of the surface evolution, which gives improved cavity performance, advanced surface analysis techniques (e.g. SEM/EDX, TEM, XPS, TOF-SIMS) are utilized. Additionally, a small furnace just for samples was set up to change and explore the parameter space of the infusion recipe. Results of these analyses, their implications for the cavity R&D and next steps are presented.

Poster MOP023 [3.759 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-MOP023

About •

paper received ※ 23 June 2019 paper accepted ※ 30 June 2019 issue date ※ 14 August 2019

Export •

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