SRF2019 - List of Keywords (interface)

Paper	Title	Other Keywords	Page
MOP060	INFN-LASA for the PIP-II Project	cavity, niobium, SRF, linac	205
	R. Paparella, M. Bertucci, A. Bignami, A. Bosotti, M. Chiodini, A. D’Ambros, P. Michelato, L. Monaco, D. Sertore INFN/LASA, Segrate (MI), Italy J.F. Chen SARI-CAS, Pudong, Shanghai, People’s Republic of China C. Pagani Università degli Studi di Milano & INFN, Segrate, Italy L. Sagliano ESS, Lund, Sweden
	INFN-LASA joined the international effort for the PIP-II project in Fermilab to build the 650 MHz superconducting cavities realizing the low-beta section of the 800 MeV proton linac. After developing the electro-magnetic and mechanical design, INFN-Milano started the prototyping phase by producing five single-cells and two complete 5-cells cavities. This paper reports the status of PIP-II activities at INFN-LASA summarizing manufacturing experience and preliminary experimental results.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-MOP060
About •	paper received ※ 24 June 2019 paper accepted ※ 30 June 2019 issue date ※ 14 August 2019
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MOP082	Measurement of the Vibration Response of the EXFEL RF Coupler and Comparison With Simulated Data (Finite Element Analyses)	FEL, cryomodule, acceleration, resonance	273
	S. Barbanotti, C. Engling, K. Jensch DESY, Hamburg, Germany
	The coupler is one of the main and most sensitive components of the European X-ray Free Electron Laser (EXFEL) superconducting cryomodule. More than 800 couplers were transported for more than 800 km assembled in a cryomodule during the assembly phase of the EXFEL without any visible damage. However, in a different project, a very similar coupler design showed a week point in one of the bellows when transported over a similar distance with a comparable transport set up. Therefore we decided to further study the coupler behaviour: we investigated the frequency response of the coupler on a vibration table in a controlled environment for different road and loading conditions and compared the data with simulated ones. This paper present the work performed so far and our conclusions.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-MOP082
About •	paper received ※ 18 June 2019 paper accepted ※ 29 June 2019 issue date ※ 14 August 2019
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MOP094	Design Strategy of the PIP-II Cryomodules	cryomodule, cavity, vacuum, cryogenics	307
	V. Roger, S.K. Chandrasekaran, D. Passarelli Fermilab, Batavia, Illinois, USA
	Funding: This manuscript has been authored by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the U.S. Department of Energy, Office of Science, Office of High Energy Physics The Proton Improvement Plan II (PIP-II) is the first U.S. accelerator project that will have significant contributions from international partners. Research institutions in India, Italy, UK and France will build major components of the particle accelerator. The High Beta 650 MHz (HB650) prototype cryomodule is being designed jointly between Fermilab (USA), CEA (France), STFC (UK) and RRCAT (India). The assembly of this prototype cryomodule will be done at Fermilab whereas the production cryomodules will be assembled in UK. Concerning the Low Beta 650 MHz (LB650) cryomodules, they will be designed and assembled at CEA. To reduce the cost of the project and to increase the quality it is essential to define a design strategy for each cryomodule which includes a degree of standardization. In this way, the lessons learned of each prototype cryomodule will have a great impact not only on one cryomodule type but on all cryomodules. An international joint design brings also additional challenges to the project: which unit system should be used? Should a common project lifecycle management system be used for all partners? How to transport the cryomodules overseas.
	Poster MOP094 [1.117 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-MOP094
About •	paper received ※ 21 June 2019 paper accepted ※ 30 June 2019 issue date ※ 14 August 2019
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TUFUB8	CVD Coated Copper Substrate SRF Cavity Research at Cornell University	cavity, SRF, niobium, target	381
	M. Ge, T. Gruber, J.J. Kaufman, M. Liepe, J.T. Maniscalco, T.E. Oseroff, R.D. Porter, Z. Sun Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA V.M. Arrieta, S.R. McNeal Ultramet, Pacoima, California, USA
	Chemical vapor deposition (CVD) is a promising alternative to conventional sputter techniques for coating copper substrate cavities with high-quality superconducting films. Through multiple SRF-related DOE SBIR projects, Ultramet has developed CVD processes and CVD reactor designs for SRF cavities, and Cornell University has conducted extensive RF testing of CVD coated surfaces. Here we report results from thin-film CVD Nb₃Sn coated copper test plates, and for thick-film CVD niobium on copper including full-scale single cell 1.3 GHz copper substrate cavities. Detailed optical inspection and surface characterization show high-quality and well-adhered coatings. No copper contamination is found. The Nb₃Sn coated plates have a uniform Nb₃Sn coating with a slightly low tin concentration (19 -22%), but a BCS resistance well in agreement with predictions. The CVD Nb coatings on copper plates demonstrate excellent adhesion characteristics and exceeded surface fields of 50 mT without showing signs of a strong Q-slope that is frequently observed in sputtered Nb cavities. Multiple single-cell 1.3 GHz copper cavities have been coated to date at Ultramet, and results from RF testing of these are presented and discussed.
	Slides TUFUB8 [12.488 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-TUFUB8
About •	paper received ※ 01 July 2019 paper accepted ※ 05 July 2019 issue date ※ 14 August 2019
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TUP014	Mechanical Design and Fabrication Aspects of Prototype SSR2 Jacketed Cavities	cavity, SRF, cryomodule, electron	424
	M. Parise, D. Passarelli, F. Ruiu Fermilab, Batavia, Illinois, USA P. Duchesne, D. Longuevergne, D. Reynet Université Paris-Saclay, CNRS/IN2P3, IJCLab, Orsay, France
	A total of 35 Superconducting SSR2 spoke cavities will be installed in the PIP II SRF linac at Fermilab and a total of 8 prototype SSR2 cavities will be manufactured for the prototype cryomodule. In this paper, the mechanical design and fabrication aspects of the prototype jacketed SSR2 cavity will be presented. RF and mechanical design activities were conducted in parallel directly on the jacketed cavity in order to minimize the number of design iterations. Also, the lessons learned from other spoke cavities experiences (i.e. SSR1 at Fermilab and ESS double spoke at IPNO) were considered since the early stage of the design.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-TUP014
About •	paper received ※ 23 June 2019 paper accepted ※ 30 June 2019 issue date ※ 14 August 2019
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TUP083	Performance of the 650 MHz SRF Cavity Tuner for PIP II Project	cavity, SRF, cryomodule, resonance	652
	Y.M. Pischalnikov, S.K. Chandrasekaran, S. Cheban, I.V. Gonin, T.N. Khabiboulline, V.P. Yakovlev, J.C. Yun Fermilab, Batavia, Illinois, USA C. Contreras-Martinez FRIB, East Lansing, Michigan, USA
	The PIP-II linac will include fifty seven 650MHz SRF cavities. Each cavity will be equipped with tuner for coarse and fine frequency tuning. Design and operations parameters will be discussed. Results from room temperature tests with prototype tuner installed on a 650MHz ¿_G=0.90 elliptical cavity will be presented.
	Poster TUP083 [1.567 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-TUP083
About •	paper received ※ 23 June 2019 paper accepted ※ 02 July 2019 issue date ※ 14 August 2019
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THFUA6	Nb₃Sn Films for SRF Cavities: Genesis and RF Properties	cavity, niobium, SRF, experiment	810
	U. Pudasaini, M.J. Kelley The College of William and Mary, Williamsburg, Virginia, USA J.W. Angle, M.J. Kelley, J. Tuggle Virginia Polytechnic Institute and State University, Blacksburg, USA G.V. Eremeev, M.J. Kelley, C.E. Reece JLab, Newport News, Virginia, USA
	Funding: Partially authored by Jefferson Science Associates under contract no. DE¬AC05¬06OR23177. Supported by Office of High Energy Physics under grants DE-SC-0014475 to the College of William and DE-SC-0018918 to Virginia Tech. Understanding of Nb₃Sn nucleation and growth is essential to the progress with Nb₃Sn vapor diffusion coatings of SRF cavities. Samples representing different stages of Nb₃Sn formation have been produced and examined to elucidate the effects of nucleation, growth, process conditions, and impurities. Nb₃Sn films from few hundreds of nm up to ~15 µm were grown and characterized using AFM, SEM/EDS, XPS, EBSD, SIMS, and SAM. Microscopic examinations of samples suggest the mechanisms behind Nb₃Sn thin film nucleation and growth. RF measurements of coated cavities were combined with material characterization of witness samples to adapt the coating process in "Siemens" coating configuration. Understanding obtained from sample studies, applied to cavities, resulted in Nb₃Sn cavity with quality factor 2 ×10¹⁰ at 15 MV/m accelerating gradient at 4 K, without "Wuppertal" Q-slope. We discuss the genesis of the Nb₃Sn thin film in a typical tin vapor diffusion process, and its consequences to the coating of SRF cavities.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-THFUA6
About •	paper received ※ 23 June 2019 paper accepted ※ 29 June 2019 issue date ※ 14 August 2019
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THP009	Pulse Laser Annealing of Niobium Film on Copper for SRF Cavities	laser, niobium, cavity, experiment	848
	Y. Yang, X.Y. Lu, W.W. Tan, L. Xiao, D. Xie, L. Zhu PKU, Beijing, People’s Republic of China
	Thin film cavities were proposed as the most promis-ing next generation superconducting cavities. The chal-lenges are improving the surface superconducting per-formance and reducing defects of the coating film, which can be greatly solved by laser annealing. Laser annealing system has been set up in Peking University, and experi-ments with niobium thin film sample have been carried out. Superconducting performance and other properties of Nb/Cu samples before and after annealing were com-pared. Recrystallization happened and surface structure improved a lot according to the results.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-THP009
About •	paper received ※ 22 June 2019 paper accepted ※ 30 June 2019 issue date ※ 14 August 2019
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THP017	Crystallographic Characterization of Nb₃Sn Coatings and N-Doped Niobium via EBSD and SIMS	niobium, SRF, electron, cavity	871
	J.W. Angle, M.J. Kelley, J. Tuggle Virginia Polytechnic Institute and State University, Blacksburg, USA G.V. Eremeev, M.J. Kelley, C.E. Reece JLab, Newport News, Virginia, USA M.J. Kelley, U. Pudasaini The College of William and Mary, Williamsburg, Virginia, USA
	Historically, niobium has been used as the superconducting material in SRF cavities. Due the high operational costs, other materials are currently being considered. Nb₃Sn coatings have been investigated over the past several decades, motivated by potentially higher operating temperatures. More recently niobium has been doped with nitrogen to improve the quality factor (Q). Currently, a need for better understanding still exists for both mechanisms. EBSD has been shown to be a viable technique to determine the crystallographic orientation and the size of the Nb₃Sn grains. The EBSD maps obtained show a bimodal distribution of grain sizes with smaller Nb₃Sn grains found present near the Nb₃Sn/Nb interface. In addition to the Nb₃Sn coatings, N-doped niobium coupons were analyzed by EBSD and found that the coupon had preferred surface orientation. The EBSD analysis was found to be vital as specific grains could be targeted in SIMS to better understand the diffusion of nitrogen with respect to crystal orientation.
	Poster THP017 [2.571 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-THP017
About •	paper received ※ 23 June 2019 paper accepted ※ 29 June 2019 issue date ※ 14 August 2019
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THP078	CERN’s SRF Test Stand for Cavity Performance Measurements	cavity, controls, LLRF, operation	1082
	N. Stapley, J. Bastard, M.R. Coly, A.E. Ivanov, A. Macpherson, N.C. Shipman, K. Turaj CERN, Geneva, Switzerland I. Ben-Zvi BNL, Upton, New York, USA A. Castilla Cockcroft Institute, Lancaster University, Lancaster, United Kingdom K. Hernandez-Chahin Universidad de Guanajuato, División de Ciencias e Ingenierías, León, Mexico M. Wartak, A. Zwozniak IFJ-PAN, Kraków, Poland
	Recent deployment of a digital LLRF system within the cavity testing framework of CERN’s vertical test cryostats has permitted a full revamp of cavity performance validation. With both full continuous and pulse mode operation, steady state a transient RF behaviour can be effectively probed. Due to direct and integrated control and monitoring of environmental test conditions, standard and novel RF measurement procedures have been developed and integrated into the testing infrastructure, along with a coherent data flow of high granularity measurement data. We present an overview of this cavity measurement system and address the underlying architectural structure, data handling and integration of user interfaces. In addition we highlight the benefits of variety of RF cavity measurements that can now be accommodated in our large 2 K cryostats.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-THP078
About •	paper received ※ 23 June 2019 paper accepted ※ 30 June 2019 issue date ※ 14 August 2019
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THP088	Updates on the Inspection System for SRF Cavities	cavity, controls, superconducting-cavity, GUI	1111
	Y. Iwashita, H. Tongu Kyoto ICR, Uji, Kyoto, Japan H. Hayano KEK, Ibaraki, Japan Y. Kuriyama Kyoto University, Research Reactor Institute, Osaka, Japan
	Optical inspections on superconducting cavities are familiar to those who are involved in the cavity fabrications. Further improvements on the Kyoto Camera have been carried out these years together with further processing technique developments, such as removing found defects by local grinding techniques. Improvements on Kyoto Camera includes implementation of color LEDs for illumination system, which improves the inspection efficiency. These progresses will be reported.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-THP088
About •	paper received ※ 02 July 2019 paper accepted ※ 03 July 2019 issue date ※ 14 August 2019
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THP091	Upgrade of the Fermilab Spoke Test Cryostat for Testing of PIP-II 650 MHz 5-Cell Elliptical Cavities	cavity, vacuum, MMI, cryogenics	1124
	A.I. Sukhanov, S.K. Chandrasekaran, B.M. Hanna, T.H. Nicol, J.P. Ozelis, Y.M. Pischalnikov, D. Plant, O.V. Prokofiev, O.V. Pronitchev, V. Roger, W. Schappert, I. Terechkine, V.P. Yakovlev Fermilab, Batavia, Illinois, USA C. Contreras-Martinez FRIB, East Lansing, Michigan, USA
	Design of the high beta 650 MHz prototype cryomodule for PIP-II is currently undergoing at Fermilab. The cryomodule includes six 5-cell elliptical SRF cavities with accelerating voltage up to 20 MV and low heat dissipation (Q₀ > 3·10^zEhNZeHn). Characterization of performance of fully integrated jacketed cavities with high power coupler and tuner is crucial for the project. Such a characterization of jacketed cavity requires a horizontal test cryostat. Existing horizontal testing facilities at Fermilab, Horizontal Test Stand (HTS) and Spoke Test Cryostat (STC), are not large enough to accommodate jacketed 650 MHz 5-cell cavity. An upgrade of the STC is proposed to install extension to the cryostat and modify cryogenic connections and RF infrastructure to provide testing of 650 MHz cavities. In this paper we describe STC upgrade and commissioning of the upgraded facility. We discuss mitigation of issues and problems specific for testing of high Q₀ 650 MHz cavities, which require low residual magnetic field and low acoustic and mechanical vibrations environment.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-THP091
About •	paper received ※ 23 June 2019 paper accepted ※ 30 June 2019 issue date ※ 14 August 2019
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FRCAB8	Systematic Studies of the Second Sound Method for Quench Detection of Superconducting Radio Frequency Cavities	cavity, simulation, radio-frequency, diagnostics	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
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Paper

Title

Other Keywords

Page

MOP060

INFN-LASA for the PIP-II Project

cavity, niobium, SRF, linac

205

R. Paparella, M. Bertucci, A. Bignami, A. Bosotti, M. Chiodini, A. D’Ambros, P. Michelato, L. Monaco, D. Sertore
INFN/LASA, Segrate (MI), Italy
J.F. Chen
SARI-CAS, Pudong, Shanghai, People’s Republic of China
C. Pagani
Università degli Studi di Milano & INFN, Segrate, Italy
L. Sagliano
ESS, Lund, Sweden

INFN-LASA joined the international effort for the PIP-II project in Fermilab to build the 650 MHz superconducting cavities realizing the low-beta section of the 800 MeV proton linac. After developing the electro-magnetic and mechanical design, INFN-Milano started the prototyping phase by producing five single-cells and two complete 5-cells cavities. This paper reports the status of PIP-II activities at INFN-LASA summarizing manufacturing experience and preliminary experimental results.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-MOP060

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paper received ※ 24 June 2019 paper accepted ※ 30 June 2019 issue date ※ 14 August 2019

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MOP082

Measurement of the Vibration Response of the EXFEL RF Coupler and Comparison With Simulated Data (Finite Element Analyses)

FEL, cryomodule, acceleration, resonance

273

S. Barbanotti, C. Engling, K. Jensch
DESY, Hamburg, Germany

The coupler is one of the main and most sensitive components of the European X-ray Free Electron Laser (EXFEL) superconducting cryomodule. More than 800 couplers were transported for more than 800 km assembled in a cryomodule during the assembly phase of the EXFEL without any visible damage. However, in a different project, a very similar coupler design showed a week point in one of the bellows when transported over a similar distance with a comparable transport set up. Therefore we decided to further study the coupler behaviour: we investigated the frequency response of the coupler on a vibration table in a controlled environment for different road and loading conditions and compared the data with simulated ones. This paper present the work performed so far and our conclusions.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-MOP082

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paper received ※ 18 June 2019 paper accepted ※ 29 June 2019 issue date ※ 14 August 2019

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MOP094

Design Strategy of the PIP-II Cryomodules

cryomodule, cavity, vacuum, cryogenics

307

V. Roger, S.K. Chandrasekaran, D. Passarelli
Fermilab, Batavia, Illinois, USA

Funding: This manuscript has been authored by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the U.S. Department of Energy, Office of Science, Office of High Energy Physics
The Proton Improvement Plan II (PIP-II) is the first U.S. accelerator project that will have significant contributions from international partners. Research institutions in India, Italy, UK and France will build major components of the particle accelerator. The High Beta 650 MHz (HB650) prototype cryomodule is being designed jointly between Fermilab (USA), CEA (France), STFC (UK) and RRCAT (India). The assembly of this prototype cryomodule will be done at Fermilab whereas the production cryomodules will be assembled in UK. Concerning the Low Beta 650 MHz (LB650) cryomodules, they will be designed and assembled at CEA. To reduce the cost of the project and to increase the quality it is essential to define a design strategy for each cryomodule which includes a degree of standardization. In this way, the lessons learned of each prototype cryomodule will have a great impact not only on one cryomodule type but on all cryomodules. An international joint design brings also additional challenges to the project: which unit system should be used? Should a common project lifecycle management system be used for all partners? How to transport the cryomodules overseas.

Poster MOP094 [1.117 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-MOP094

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

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TUFUB8

CVD Coated Copper Substrate SRF Cavity Research at Cornell University

cavity, SRF, niobium, target

381

M. Ge, T. Gruber, J.J. Kaufman, M. Liepe, J.T. Maniscalco, T.E. Oseroff, R.D. Porter, Z. Sun
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
V.M. Arrieta, S.R. McNeal
Ultramet, Pacoima, California, USA

Chemical vapor deposition (CVD) is a promising alternative to conventional sputter techniques for coating copper substrate cavities with high-quality superconducting films. Through multiple SRF-related DOE SBIR projects, Ultramet has developed CVD processes and CVD reactor designs for SRF cavities, and Cornell University has conducted extensive RF testing of CVD coated surfaces. Here we report results from thin-film CVD Nb₃Sn coated copper test plates, and for thick-film CVD niobium on copper including full-scale single cell 1.3 GHz copper substrate cavities. Detailed optical inspection and surface characterization show high-quality and well-adhered coatings. No copper contamination is found. The Nb₃Sn coated plates have a uniform Nb₃Sn coating with a slightly low tin concentration (19 -22%), but a BCS resistance well in agreement with predictions. The CVD Nb coatings on copper plates demonstrate excellent adhesion characteristics and exceeded surface fields of 50 mT without showing signs of a strong Q-slope that is frequently observed in sputtered Nb cavities. Multiple single-cell 1.3 GHz copper cavities have been coated to date at Ultramet, and results from RF testing of these are presented and discussed.

Slides TUFUB8 [12.488 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-TUFUB8

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paper received ※ 01 July 2019 paper accepted ※ 05 July 2019 issue date ※ 14 August 2019

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TUP014

Mechanical Design and Fabrication Aspects of Prototype SSR2 Jacketed Cavities

cavity, SRF, cryomodule, electron

424

M. Parise, D. Passarelli, F. Ruiu
Fermilab, Batavia, Illinois, USA
P. Duchesne, D. Longuevergne, D. Reynet
Université Paris-Saclay, CNRS/IN2P3, IJCLab, Orsay, France

A total of 35 Superconducting SSR2 spoke cavities will be installed in the PIP II SRF linac at Fermilab and a total of 8 prototype SSR2 cavities will be manufactured for the prototype cryomodule. In this paper, the mechanical design and fabrication aspects of the prototype jacketed SSR2 cavity will be presented. RF and mechanical design activities were conducted in parallel directly on the jacketed cavity in order to minimize the number of design iterations. Also, the lessons learned from other spoke cavities experiences (i.e. SSR1 at Fermilab and ESS double spoke at IPNO) were considered since the early stage of the design.

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reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-TUP014

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

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TUP083

Performance of the 650 MHz SRF Cavity Tuner for PIP II Project

cavity, SRF, cryomodule, resonance

652

Y.M. Pischalnikov, S.K. Chandrasekaran, S. Cheban, I.V. Gonin, T.N. Khabiboulline, V.P. Yakovlev, J.C. Yun
Fermilab, Batavia, Illinois, USA
C. Contreras-Martinez
FRIB, East Lansing, Michigan, USA

The PIP-II linac will include fifty seven 650MHz SRF cavities. Each cavity will be equipped with tuner for coarse and fine frequency tuning. Design and operations parameters will be discussed. Results from room temperature tests with prototype tuner installed on a 650MHz ¿_G=0.90 elliptical cavity will be presented.

Poster TUP083 [1.567 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-TUP083

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paper received ※ 23 June 2019 paper accepted ※ 02 July 2019 issue date ※ 14 August 2019

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THFUA6

Nb₃Sn Films for SRF Cavities: Genesis and RF Properties

cavity, niobium, SRF, experiment

810

U. Pudasaini, M.J. Kelley
The College of William and Mary, Williamsburg, Virginia, USA
J.W. Angle, M.J. Kelley, J. Tuggle
Virginia Polytechnic Institute and State University, Blacksburg, USA
G.V. Eremeev, M.J. Kelley, C.E. Reece
JLab, Newport News, Virginia, USA

Funding: Partially authored by Jefferson Science Associates under contract no. DE¬AC05¬06OR23177. Supported by Office of High Energy Physics under grants DE-SC-0014475 to the College of William and DE-SC-0018918 to Virginia Tech.
Understanding of Nb₃Sn nucleation and growth is essential to the progress with Nb₃Sn vapor diffusion coatings of SRF cavities. Samples representing different stages of Nb₃Sn formation have been produced and examined to elucidate the effects of nucleation, growth, process conditions, and impurities. Nb₃Sn films from few hundreds of nm up to ~15 µm were grown and characterized using AFM, SEM/EDS, XPS, EBSD, SIMS, and SAM. Microscopic examinations of samples suggest the mechanisms behind Nb₃Sn thin film nucleation and growth. RF measurements of coated cavities were combined with material characterization of witness samples to adapt the coating process in "Siemens" coating configuration. Understanding obtained from sample studies, applied to cavities, resulted in Nb₃Sn cavity with quality factor 2 ×10¹⁰ at 15 MV/m accelerating gradient at 4 K, without "Wuppertal" Q-slope. We discuss the genesis of the Nb₃Sn thin film in a typical tin vapor diffusion process, and its consequences to the coating of SRF cavities.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-THFUA6

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paper received ※ 23 June 2019 paper accepted ※ 29 June 2019 issue date ※ 14 August 2019

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THP009

Pulse Laser Annealing of Niobium Film on Copper for SRF Cavities

laser, niobium, cavity, experiment

848

Y. Yang, X.Y. Lu, W.W. Tan, L. Xiao, D. Xie, L. Zhu
PKU, Beijing, People’s Republic of China

Thin film cavities were proposed as the most promis-ing next generation superconducting cavities. The chal-lenges are improving the surface superconducting per-formance and reducing defects of the coating film, which can be greatly solved by laser annealing. Laser annealing system has been set up in Peking University, and experi-ments with niobium thin film sample have been carried out. Superconducting performance and other properties of Nb/Cu samples before and after annealing were com-pared. Recrystallization happened and surface structure improved a lot according to the results.

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reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-THP009

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paper received ※ 22 June 2019 paper accepted ※ 30 June 2019 issue date ※ 14 August 2019

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THP017

Crystallographic Characterization of Nb₃Sn Coatings and N-Doped Niobium via EBSD and SIMS

niobium, SRF, electron, cavity

871

J.W. Angle, M.J. Kelley, J. Tuggle
Virginia Polytechnic Institute and State University, Blacksburg, USA
G.V. Eremeev, M.J. Kelley, C.E. Reece
JLab, Newport News, Virginia, USA
M.J. Kelley, U. Pudasaini
The College of William and Mary, Williamsburg, Virginia, USA

Historically, niobium has been used as the superconducting material in SRF cavities. Due the high operational costs, other materials are currently being considered. Nb₃Sn coatings have been investigated over the past several decades, motivated by potentially higher operating temperatures. More recently niobium has been doped with nitrogen to improve the quality factor (Q). Currently, a need for better understanding still exists for both mechanisms. EBSD has been shown to be a viable technique to determine the crystallographic orientation and the size of the Nb₃Sn grains. The EBSD maps obtained show a bimodal distribution of grain sizes with smaller Nb₃Sn grains found present near the Nb₃Sn/Nb interface. In addition to the Nb₃Sn coatings, N-doped niobium coupons were analyzed by EBSD and found that the coupon had preferred surface orientation. The EBSD analysis was found to be vital as specific grains could be targeted in SIMS to better understand the diffusion of nitrogen with respect to crystal orientation.

Poster THP017 [2.571 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-THP017

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paper received ※ 23 June 2019 paper accepted ※ 29 June 2019 issue date ※ 14 August 2019

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THP078

CERN’s SRF Test Stand for Cavity Performance Measurements

cavity, controls, LLRF, operation

1082

N. Stapley, J. Bastard, M.R. Coly, A.E. Ivanov, A. Macpherson, N.C. Shipman, K. Turaj
CERN, Geneva, Switzerland
I. Ben-Zvi
BNL, Upton, New York, USA
A. Castilla
Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
K. Hernandez-Chahin
Universidad de Guanajuato, División de Ciencias e Ingenierías, León, Mexico
M. Wartak, A. Zwozniak
IFJ-PAN, Kraków, Poland

Recent deployment of a digital LLRF system within the cavity testing framework of CERN’s vertical test cryostats has permitted a full revamp of cavity performance validation. With both full continuous and pulse mode operation, steady state a transient RF behaviour can be effectively probed. Due to direct and integrated control and monitoring of environmental test conditions, standard and novel RF measurement procedures have been developed and integrated into the testing infrastructure, along with a coherent data flow of high granularity measurement data. We present an overview of this cavity measurement system and address the underlying architectural structure, data handling and integration of user interfaces. In addition we highlight the benefits of variety of RF cavity measurements that can now be accommodated in our large 2 K cryostats.

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reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-THP078

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

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THP088

Updates on the Inspection System for SRF Cavities

cavity, controls, superconducting-cavity, GUI

1111

Y. Iwashita, H. Tongu
Kyoto ICR, Uji, Kyoto, Japan
H. Hayano
KEK, Ibaraki, Japan
Y. Kuriyama
Kyoto University, Research Reactor Institute, Osaka, Japan

Optical inspections on superconducting cavities are familiar to those who are involved in the cavity fabrications. Further improvements on the Kyoto Camera have been carried out these years together with further processing technique developments, such as removing found defects by local grinding techniques. Improvements on Kyoto Camera includes implementation of color LEDs for illumination system, which improves the inspection efficiency. These progresses will be reported.

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reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-THP088

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paper received ※ 02 July 2019 paper accepted ※ 03 July 2019 issue date ※ 14 August 2019

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THP091

Upgrade of the Fermilab Spoke Test Cryostat for Testing of PIP-II 650 MHz 5-Cell Elliptical Cavities

cavity, vacuum, MMI, cryogenics

1124

A.I. Sukhanov, S.K. Chandrasekaran, B.M. Hanna, T.H. Nicol, J.P. Ozelis, Y.M. Pischalnikov, D. Plant, O.V. Prokofiev, O.V. Pronitchev, V. Roger, W. Schappert, I. Terechkine, V.P. Yakovlev
Fermilab, Batavia, Illinois, USA
C. Contreras-Martinez
FRIB, East Lansing, Michigan, USA

Design of the high beta 650 MHz prototype cryomodule for PIP-II is currently undergoing at Fermilab. The cryomodule includes six 5-cell elliptical SRF cavities with accelerating voltage up to 20 MV and low heat dissipation (Q₀ > 3·10^zEhNZeHn). Characterization of performance of fully integrated jacketed cavities with high power coupler and tuner is crucial for the project. Such a characterization of jacketed cavity requires a horizontal test cryostat. Existing horizontal testing facilities at Fermilab, Horizontal Test Stand (HTS) and Spoke Test Cryostat (STC), are not large enough to accommodate jacketed 650 MHz 5-cell cavity. An upgrade of the STC is proposed to install extension to the cryostat and modify cryogenic connections and RF infrastructure to provide testing of 650 MHz cavities. In this paper we describe STC upgrade and commissioning of the upgraded facility. We discuss mitigation of issues and problems specific for testing of high Q₀ 650 MHz cavities, which require low residual magnetic field and low acoustic and mechanical vibrations environment.

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reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-THP091

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

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FRCAB8

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

cavity, simulation, radio-frequency, diagnostics

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]

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

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

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