SRF2019 - List of Authors (Reschke, D.)

Paper	Title	Page
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)

MOP024	Vacancy-Hydrogen Dynamics in Samples During Low Temperature Baking	83
	M. Wenskat, C. Bate, D. Reschke, H. Weise DESY, Hamburg, Germany C. Bate University of Hamburg, Hamburg, Germany M. Butterling, E. Hirschmann, M.O. Liedke, A. Wagner HZDR, Dresden, Germany J. Cizek Charles University, Prague, Czech Republic
	Funding: This work was supported by the Helmholtz Association within the topic Accelerator Research and Development (ARD) of the Matter and Technologies (MT) Program and by the BMBF under the research grant 05H18GURB1. The recent discovery of a modified low temperature baking process lead to a reduction of surface losses and an increase of the accelerating gradient of TESLA shape cavities. The hypothesis linking the accelerator performance and the treatment is the suppression of lossy nanohydrides via defect trapping, with vacancy-hydrogen complexes forming at the lower temperatures. Utilizing Doppler broadening Positron Annihilation Spectroscopy and Positron Annihilation Lifetime Spectroscopy samples made from European XFEL niobium sheets and cavity cut-outs were investigated. The evolution of vacancies, hydrogen and their interaction at different temperature levels have been studied during in-situ annealing. Measurements of niobium samples and a correlation between RF, material properties, and V-H distribution in cavity cut-outs has been done.
	Poster MOP024 [1.087 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-MOP024
About •	paper received ※ 20 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)

MOP025	Cavity Cut-out Studies of a 1.3 GHz Single-cell Cavity After a Failed Nitrogen Infusion Process	87
	M. Wenskat, C. Bate, T.F. Keller, D. Reschke DESY, Hamburg, Germany C. Bate University of Hamburg, Hamburg, Germany A. Jeromin DESY Nanolab, FS-NL, Hamburg, Germany J. Knobloch, F. Kramer, O. Kugeler, J.M. Köszegi HZB, Berlin, Germany J. Knobloch University of Siegen, Siegen, Germany
	Funding: This work was supported by the Helmholtz Association within the topic Accelerator Research and Development (ARD) of the Matter and Technologies (MT) Program and by the BMBF under the research grant 05H18GURB1. R&D on the nitrogen infusion process at DESY produced at the beginning a series of 1.3 GHz single-cell cavities which have shown severe deterioration in the vertical cold test which was completely unexpected and could not be explained. To investigate the reason for the deterioration, one of those cavities was optically inspected and a T- and H-Map test was done in collaboration with HZB. Together with 2nd Sound data, regions of interests were identified and cut from the cavity. Subsequent surface analysis techniques (SEM/EDX, SIMS, PIXE, EBSD, DB-PAS, PALS, XPS) were applied in order to identify the reason for the deterioration. Especially the differences between hot and cold spots as well as quench spots identified by T-Mapping were investigated.
	Poster MOP025 [0.975 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-MOP025
About •	paper received ※ 20 June 2019 paper accepted ※ 29 June 2019 issue date ※ 14 August 2019
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOP026	A Cross-Lab Qualification of Modified 120°C Baked Cavities	90
	M. Wenskat, D. Reschke, J. Schaffran, L. Steder, M. Wiencek DESY, Hamburg, Germany D. Bafia, A. Grassellino, O.S. Melnychuk Fermilab, Batavia, Illinois, USA A.D. Palczewski JLab, Newport News, Virginia, USA M. Wiencek IFJ-PAN, Kraków, Poland
	Funding: This work was supported by the Helmholtz Association within the topic Accelerator Research and Development (ARD) of the Matter and Technologies (MT) Program and by the BMBF under the research grant 05H18GURB1. Within a global effort to understand and standardize the nitrogen-infusion and the low T bake procedure, one large grain and two fine grain single-cell cavity were treated and tested at FNAL and then send to other labs including DESY and JLab for further studies.
	Poster MOP026 [0.813 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-MOP026
About •	paper received ※ 20 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)

MOP034	European XFEL: Accelerating Module Repair at DESY	127
	D. Kostin, J. Eschke, K. Jensch, N. Krupka, D. Reschke, S. Saegebarth, J. Schaffran, M. Schalwat, P. Schilling, M. Schmökel, S. Sievers, N. Steinhau-Kühl, E. Vogel, H. Weise, M. Wiencek, B. van der Horst DESY, Hamburg, Germany
	The European XFEL is in operation since 2017. The design projected energy of 17.5 GeV was reached, even with the last 4 main linac accelerating modules not yet installed. 2 out of 4 not installed modules did suffer from strong cavity performance degradation, namely increased field emission, and required surface processing. The first of two modules is reassembled and tested. The module test results confirm a successful repair action. The module repair and test steps are described together with cavities performance evolution.
	Poster MOP034 [1.863 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-MOP034
About •	paper received ※ 17 June 2019 paper accepted ※ 29 June 2019 issue date ※ 14 August 2019
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOP058	ESS Medium Beta Activity at INFN LASA	199
	D. Sertore, M. Bertucci, A. Bignami, A. Bosotti, M. Chiodini, A. D’Ambros, G. Fornasier, P. Michelato, L. Monaco, R. Paparella INFN/LASA, Segrate (MI), Italy S. Aurnia, O. Leonardi, A. Miraglia, G. Vecchio INFN/LNS, Catania, Italy A. Gresele, A. Visentin Ettore Zanon S.p.A., Nuclear Division, Schio, Italy C. Pagani Università degli Studi di Milano & INFN, Segrate, Italy D. Reschke, A. Sulimov, M. Wiencek DESY, Hamburg, Germany D. Rizzetto, M. Rizzi Ettore Zanon S.p.A., Schio, Italy L. Sagliano ESS, Lund, Sweden
	The industrial production of the 36 resonators (plus 2 spares) for the ESS linac started and it is steadily progressing. Cavities are delivered by industry as fully surface-treated and dressed to AMTF facility at DESY for their qualification via vertical cold-test. This paper reports the current status of the manufacturing process from sub-components to processing of the complete cavity inner surface. It also reviews the documental control strategy deployed to preserve the fulfillment of ESS requirements as well as the cavity performances demonstrated so far.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-MOP058
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)

MOP070	Investigation of the Critical RF Fields of Superconducting Cavity Connections	230
SUSP026	use link to see paper's listing under its alternate paper code
	J.C. Wolff, J.I. Iversen, D. Klinke, D. Kostin, D. Reschke, S. Sievers, A. Sulimov, J.H. Thie, M. Wiencek DESY, Hamburg, Germany R. Wendel, J.C. Wolff HAW Hamburg, Hamburg, Germany
	To optimise the length of the drift tube of a superconducting cavity (SC), it is required to know the critical value of the RF fields to prevent a potential early quench at the flange connection in case of a drift tube length reduction. To avoid changes on the SC which has been used for the tests, all RF cryogenic experiments have been carried out by using a cylinder in the center of a 1-cell cavity drift tube to increase the field magnitude at the connection. This cylinder has been designed and optimised by RF simulations to provide a field density at the connection twice as high as at a chosen reference point near the iris. Hence also a test SC with a comparatively low gradient can be used without causing field restrictions. In this contribution an approach to investigate the field limitations of 1.3 GHz TESLA-Shape SC connections and thereby the minimal drift tube length based on simulations will be presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-MOP070
About •	paper received ※ 23 June 2019 paper accepted ※ 04 July 2019 issue date ※ 14 August 2019
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUFUA6	Surface Analysis of Niobium After Thermal/Gas Treatments via Samples - Review
	A. Dangwal Pandey, T.F. Keller, H. Noei, D. Reschke, J. Schaffran, G.D.L. Semione, V. Vonk, H. Weise, M. Wenskat DESY, Hamburg, Germany C. Bate, A. Stierle University of Hamburg, Hamburg, Germany
	Thermal treatments of SRF Nb cavities - including the well-established 120°C bake and the recently reported N-infusion - are shown to improve the cavity performance significantly; however, the underlying physical phenomenon is not fully understood. A short review will be presented on surface characterization of niobium material subjected to various thermal and gas exposure protocols and how the findings correlate with observed SRF properties. Moreover, recent results obtained on single-crystal Nb samples - heated in different vacuum environments and characterised by means of X-ray photoelectron spectroscopy and grazing-incidence X-ray diffraction, electron microscopy, energy dispersive X-ray spectroscopy and time-of-flight secondary ion mass spectroscopy will be discussed.
	Slides TUFUA6 [6.968 MB]
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUP020	Statistical Analysis of the 120°C Bake Procedure of Superconducting Radio Frequency Cavities	444
	L. Steder, D. Reschke DESY, Hamburg, Germany
	DESY is and was very active in R&D related to SRF cavities. Many single and nine cell cavities with different surface treatment histories were tested vertically. Results of these cold tests are accelerating gradient and quality factor of the cavities. Using the large number of available datasets the parameters of the 120°C bake procedure, which is applied to avoid high-field Q-slope, are analysed. The impact of different durations and temperatures on accelerating gradient, quality factor and residual resistance is studied in detail and is compared to results obtained with the recently proposed procedure of modified low temperature bake. For this procedure additional four hours at temperatures around 75°C are implemented before the standard bake at about 120°C. Since the claim is, that cavities treated with such a modified procedure achieve extra-ordinary large accelerating gradients it is a very interesting research field for the European XFEL continuous wave mode upgrade. For this purpose cavities with high quality factors are needed, but in addition large maximal accelerating fields are required to maintain high energies in the pulsed operation mode of the accelerator.
	Poster TUP020 [0.747 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-TUP020
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)

TUP099	Particulate Sampling and Analysis During Refurbishment of Prototype European XFEL Cryomodule	701
	N. Krupka, C. Bate, D. Reschke, S. Saegebarth, M. Schalwat, P. Schilling, S. Sievers DESY, Hamburg, Germany
	Funding: This work was supported by the Helmholtz Association within the topic Accelerator Research and Development (ARD) of the Matter and Tech-nologies (MT) Program. The cryomodule PXFEL3₁ is one of three prototype cryomodules for the European XFEL. In preparation of the series module assembly it was used for the qualification of infrastructure and personnel at CEA Saclay. After transport and tests at DESY the cryomodule was stored for several years. Last year we decided to refurbish this module with new cavities for the installation in the FLASH accelerator. During the disassembly of the cavity string in the clean room at DESY we took several particulate samples for analysis. Optical and laser optical microscopy give us an insight on the quantity and type of the particulates. We expect to get hints where the particulates come from and how they are transported through the cavity string during transport and operation.
	Poster TUP099 [2.599 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-TUP099
About •	paper received ※ 23 June 2019 paper accepted ※ 03 July 2019 issue date ※ 14 August 2019
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THP004	Design and Fabrication of a Quadrupole-Resonator for Sample R&D	838
SUSP042	use link to see paper's listing under its alternate paper code
	R. Monroy-Villa, D. Reschke, M. Wenskat DESY, Hamburg, Germany W. Hillert, R. Monroy-Villa, M. Wenskat University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany S. Keckert, O. Kugeler, D.B. Tikhonov HZB, Berlin, Germany P. Putek, S.G. Zadeh, U. van Rienen Rostock University, Faculty of Computer Science and Electrical Engineering, Rostock, Germany U. van Rienen University of Rostock, Rostock, Germany
	Being able to obtain BCS and material properties from the same surface is necessary to gain a fundamental understanding of the evolution of SRF surfaces. A test resonator which will allow to obtain BCS properties from samples is currently under development at the University of Hamburg and DESY and is based on the Quadrupole Resonators developed and operated at CERN and HZB. The current status of the necessary infrastructure, the procurement process and design considerations are shown. In addition, an outline of the planed R&D project with the Quadrupole Resonator will be presented and first RF measurements and surface analysis results of samples will be shown
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-THP004
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)

FRCAB8	Systematic Studies of the Second Sound Method for Quench Detection of Superconducting Radio Frequency Cavities	1239
	L. Steder, B. Bein, D. Reschke DESY, Hamburg, Germany W. Hillert University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany
	DESY conducts R&D for SRF cavities, part of the manifold activities are vertical performance tests. Besides the determination of accelerating gradient and quality factor, additional sensors and diagnostic methods are used to obtain more information about the cavity behaviour and the test environment. The second sound system is a tool for spatially resolved quench detection via oscillating super-leak transducers, they record the second sound wave, generated by the quench of the superconducting Niobium. The mounting of the sensors was improved to reduce systematic uncertainties and results of a recent master thesis are presented in the following. Different reconstruction methods are used to determine the origin of the waves. The precision, constraints and limits of these are compared. To introduce an external reference and to qualify the different methods a calibration tool was used. It injects short heat pulses to resistors at exact known space and time coordinates. Results obtained by the different algorithms and measurements with the calibration tool are presented with an emphasis on the possible spatial resolution and the estimation of systematic uncertainties of the methods.
	Slides FRCAB8 [3.039 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-FRCAB8
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)

Paper

Title

Page

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)

MOP024

Vacancy-Hydrogen Dynamics in Samples During Low Temperature Baking

83

M. Wenskat, C. Bate, D. Reschke, H. Weise
DESY, Hamburg, Germany
C. Bate
University of Hamburg, Hamburg, Germany
M. Butterling, E. Hirschmann, M.O. Liedke, A. Wagner
HZDR, Dresden, Germany
J. Cizek
Charles University, Prague, Czech Republic

Funding: This work was supported by the Helmholtz Association within the topic Accelerator Research and Development (ARD) of the Matter and Technologies (MT) Program and by the BMBF under the research grant 05H18GURB1.
The recent discovery of a modified low temperature baking process lead to a reduction of surface losses and an increase of the accelerating gradient of TESLA shape cavities. The hypothesis linking the accelerator performance and the treatment is the suppression of lossy nanohydrides via defect trapping, with vacancy-hydrogen complexes forming at the lower temperatures. Utilizing Doppler broadening Positron Annihilation Spectroscopy and Positron Annihilation Lifetime Spectroscopy samples made from European XFEL niobium sheets and cavity cut-outs were investigated. The evolution of vacancies, hydrogen and their interaction at different temperature levels have been studied during in-situ annealing. Measurements of niobium samples and a correlation between RF, material properties, and V-H distribution in cavity cut-outs has been done.

Poster MOP024 [1.087 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-MOP024

About •

paper received ※ 20 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)

MOP025

Cavity Cut-out Studies of a 1.3 GHz Single-cell Cavity After a Failed Nitrogen Infusion Process

87

M. Wenskat, C. Bate, T.F. Keller, D. Reschke
DESY, Hamburg, Germany
C. Bate
University of Hamburg, Hamburg, Germany
A. Jeromin
DESY Nanolab, FS-NL, Hamburg, Germany
J. Knobloch, F. Kramer, O. Kugeler, J.M. Köszegi
HZB, Berlin, Germany
J. Knobloch
University of Siegen, Siegen, Germany

Funding: This work was supported by the Helmholtz Association within the topic Accelerator Research and Development (ARD) of the Matter and Technologies (MT) Program and by the BMBF under the research grant 05H18GURB1.
R&D on the nitrogen infusion process at DESY produced at the beginning a series of 1.3 GHz single-cell cavities which have shown severe deterioration in the vertical cold test which was completely unexpected and could not be explained. To investigate the reason for the deterioration, one of those cavities was optically inspected and a T- and H-Map test was done in collaboration with HZB. Together with 2nd Sound data, regions of interests were identified and cut from the cavity. Subsequent surface analysis techniques (SEM/EDX, SIMS, PIXE, EBSD, DB-PAS, PALS, XPS) were applied in order to identify the reason for the deterioration. Especially the differences between hot and cold spots as well as quench spots identified by T-Mapping were investigated.

Poster MOP025 [0.975 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-MOP025

About •

paper received ※ 20 June 2019 paper accepted ※ 29 June 2019 issue date ※ 14 August 2019

Export •

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

MOP026

A Cross-Lab Qualification of Modified 120°C Baked Cavities

90

M. Wenskat, D. Reschke, J. Schaffran, L. Steder, M. Wiencek
DESY, Hamburg, Germany
D. Bafia, A. Grassellino, O.S. Melnychuk
Fermilab, Batavia, Illinois, USA
A.D. Palczewski
JLab, Newport News, Virginia, USA
M. Wiencek
IFJ-PAN, Kraków, Poland

Funding: This work was supported by the Helmholtz Association within the topic Accelerator Research and Development (ARD) of the Matter and Technologies (MT) Program and by the BMBF under the research grant 05H18GURB1.
Within a global effort to understand and standardize the nitrogen-infusion and the low T bake procedure, one large grain and two fine grain single-cell cavity were treated and tested at FNAL and then send to other labs including DESY and JLab for further studies.

Poster MOP026 [0.813 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-MOP026

About •

paper received ※ 20 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)

MOP034

European XFEL: Accelerating Module Repair at DESY

127

D. Kostin, J. Eschke, K. Jensch, N. Krupka, D. Reschke, S. Saegebarth, J. Schaffran, M. Schalwat, P. Schilling, M. Schmökel, S. Sievers, N. Steinhau-Kühl, E. Vogel, H. Weise, M. Wiencek, B. van der Horst
DESY, Hamburg, Germany

The European XFEL is in operation since 2017. The design projected energy of 17.5 GeV was reached, even with the last 4 main linac accelerating modules not yet installed. 2 out of 4 not installed modules did suffer from strong cavity performance degradation, namely increased field emission, and required surface processing. The first of two modules is reassembled and tested. The module test results confirm a successful repair action. The module repair and test steps are described together with cavities performance evolution.

Poster MOP034 [1.863 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-MOP034

About •

paper received ※ 17 June 2019 paper accepted ※ 29 June 2019 issue date ※ 14 August 2019

Export •

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

MOP058

ESS Medium Beta Activity at INFN LASA

199

D. Sertore, M. Bertucci, A. Bignami, A. Bosotti, M. Chiodini, A. D’Ambros, G. Fornasier, P. Michelato, L. Monaco, R. Paparella
INFN/LASA, Segrate (MI), Italy
S. Aurnia, O. Leonardi, A. Miraglia, G. Vecchio
INFN/LNS, Catania, Italy
A. Gresele, A. Visentin
Ettore Zanon S.p.A., Nuclear Division, Schio, Italy
C. Pagani
Università degli Studi di Milano & INFN, Segrate, Italy
D. Reschke, A. Sulimov, M. Wiencek
DESY, Hamburg, Germany
D. Rizzetto, M. Rizzi
Ettore Zanon S.p.A., Schio, Italy
L. Sagliano
ESS, Lund, Sweden

The industrial production of the 36 resonators (plus 2 spares) for the ESS linac started and it is steadily progressing. Cavities are delivered by industry as fully surface-treated and dressed to AMTF facility at DESY for their qualification via vertical cold-test. This paper reports the current status of the manufacturing process from sub-components to processing of the complete cavity inner surface. It also reviews the documental control strategy deployed to preserve the fulfillment of ESS requirements as well as the cavity performances demonstrated so far.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-MOP058

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)

MOP070

Investigation of the Critical RF Fields of Superconducting Cavity Connections

230

SUSP026

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

J.C. Wolff, J.I. Iversen, D. Klinke, D. Kostin, D. Reschke, S. Sievers, A. Sulimov, J.H. Thie, M. Wiencek
DESY, Hamburg, Germany
R. Wendel, J.C. Wolff
HAW Hamburg, Hamburg, Germany

To optimise the length of the drift tube of a superconducting cavity (SC), it is required to know the critical value of the RF fields to prevent a potential early quench at the flange connection in case of a drift tube length reduction. To avoid changes on the SC which has been used for the tests, all RF cryogenic experiments have been carried out by using a cylinder in the center of a 1-cell cavity drift tube to increase the field magnitude at the connection. This cylinder has been designed and optimised by RF simulations to provide a field density at the connection twice as high as at a chosen reference point near the iris. Hence also a test SC with a comparatively low gradient can be used without causing field restrictions. In this contribution an approach to investigate the field limitations of 1.3 GHz TESLA-Shape SC connections and thereby the minimal drift tube length based on simulations will be presented.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-MOP070

About •

paper received ※ 23 June 2019 paper accepted ※ 04 July 2019 issue date ※ 14 August 2019

Export •

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

TUFUA6

Surface Analysis of Niobium After Thermal/Gas Treatments via Samples - Review

A. Dangwal Pandey, T.F. Keller, H. Noei, D. Reschke, J. Schaffran, G.D.L. Semione, V. Vonk, H. Weise, M. Wenskat
DESY, Hamburg, Germany
C. Bate, A. Stierle
University of Hamburg, Hamburg, Germany

Thermal treatments of SRF Nb cavities - including the well-established 120°C bake and the recently reported N-infusion - are shown to improve the cavity performance significantly; however, the underlying physical phenomenon is not fully understood. A short review will be presented on surface characterization of niobium material subjected to various thermal and gas exposure protocols and how the findings correlate with observed SRF properties. Moreover, recent results obtained on single-crystal Nb samples - heated in different vacuum environments and characterised by means of X-ray photoelectron spectroscopy and grazing-incidence X-ray diffraction, electron microscopy, energy dispersive X-ray spectroscopy and time-of-flight secondary ion mass spectroscopy will be discussed.

Slides TUFUA6 [6.968 MB]

Export •

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

TUP020

Statistical Analysis of the 120°C Bake Procedure of Superconducting Radio Frequency Cavities

444

L. Steder, D. Reschke
DESY, Hamburg, Germany

DESY is and was very active in R&D related to SRF cavities. Many single and nine cell cavities with different surface treatment histories were tested vertically. Results of these cold tests are accelerating gradient and quality factor of the cavities. Using the large number of available datasets the parameters of the 120°C bake procedure, which is applied to avoid high-field Q-slope, are analysed. The impact of different durations and temperatures on accelerating gradient, quality factor and residual resistance is studied in detail and is compared to results obtained with the recently proposed procedure of modified low temperature bake. For this procedure additional four hours at temperatures around 75°C are implemented before the standard bake at about 120°C. Since the claim is, that cavities treated with such a modified procedure achieve extra-ordinary large accelerating gradients it is a very interesting research field for the European XFEL continuous wave mode upgrade. For this purpose cavities with high quality factors are needed, but in addition large maximal accelerating fields are required to maintain high energies in the pulsed operation mode of the accelerator.

Poster TUP020 [0.747 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-TUP020

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)

TUP099

Particulate Sampling and Analysis During Refurbishment of Prototype European XFEL Cryomodule

701

N. Krupka, C. Bate, D. Reschke, S. Saegebarth, M. Schalwat, P. Schilling, S. Sievers
DESY, Hamburg, Germany

Funding: This work was supported by the Helmholtz Association within the topic Accelerator Research and Development (ARD) of the Matter and Tech-nologies (MT) Program.
The cryomodule PXFEL3₁ is one of three prototype cryomodules for the European XFEL. In preparation of the series module assembly it was used for the qualification of infrastructure and personnel at CEA Saclay. After transport and tests at DESY the cryomodule was stored for several years. Last year we decided to refurbish this module with new cavities for the installation in the FLASH accelerator. During the disassembly of the cavity string in the clean room at DESY we took several particulate samples for analysis. Optical and laser optical microscopy give us an insight on the quantity and type of the particulates. We expect to get hints where the particulates come from and how they are transported through the cavity string during transport and operation.

Poster TUP099 [2.599 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-TUP099

About •

paper received ※ 23 June 2019 paper accepted ※ 03 July 2019 issue date ※ 14 August 2019

Export •

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

THP004

Design and Fabrication of a Quadrupole-Resonator for Sample R&D

838

SUSP042

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

R. Monroy-Villa, D. Reschke, M. Wenskat
DESY, Hamburg, Germany
W. Hillert, R. Monroy-Villa, M. Wenskat
University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany
S. Keckert, O. Kugeler, D.B. Tikhonov
HZB, Berlin, Germany
P. Putek, S.G. Zadeh, U. van Rienen
Rostock University, Faculty of Computer Science and Electrical Engineering, Rostock, Germany
U. van Rienen
University of Rostock, Rostock, Germany

Being able to obtain BCS and material properties from the same surface is necessary to gain a fundamental understanding of the evolution of SRF surfaces. A test resonator which will allow to obtain BCS properties from samples is currently under development at the University of Hamburg and DESY and is based on the Quadrupole Resonators developed and operated at CERN and HZB. The current status of the necessary infrastructure, the procurement process and design considerations are shown. In addition, an outline of the planed R&D project with the Quadrupole Resonator will be presented and first RF measurements and surface analysis results of samples will be shown

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-THP004

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)

FRCAB8

Systematic Studies of the Second Sound Method for Quench Detection of Superconducting Radio Frequency Cavities

1239

L. Steder, B. Bein, D. Reschke
DESY, Hamburg, Germany
W. Hillert
University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany

DESY conducts R&D for SRF cavities, part of the manifold activities are vertical performance tests. Besides the determination of accelerating gradient and quality factor, additional sensors and diagnostic methods are used to obtain more information about the cavity behaviour and the test environment. The second sound system is a tool for spatially resolved quench detection via oscillating super-leak transducers, they record the second sound wave, generated by the quench of the superconducting Niobium. The mounting of the sensors was improved to reduce systematic uncertainties and results of a recent master thesis are presented in the following. Different reconstruction methods are used to determine the origin of the waves. The precision, constraints and limits of these are compared. To introduce an external reference and to qualify the different methods a calibration tool was used. It injects short heat pulses to resistors at exact known space and time coordinates. Results obtained by the different algorithms and measurements with the calibration tool are presented with an emphasis on the possible spatial resolution and the estimation of systematic uncertainties of the methods.

Slides FRCAB8 [3.039 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-FRCAB8

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)