SRF2021 - List of Authors (Pira, C.)

Paper	Title	Page
SUPCAV005	Current Status of the ALPI Linac Upgrade for the SPES Facilities at INFN LNL	11
	A. Tsymbaliuk, D. Bortolato, F. Chiurlotto, E. Chyhyrynets, G. Keppel, E. Munaron, C. Pira, F. Stivanello INFN/LNL, Legnaro (PD), Italy E. Chyhyrynets Università degli Studi di Padova, Padova, Italy A. Tsymbaliuk UNIFE, Ferrara, Italy
	The SPES project is based at INFN LNL and covers basic research in nuclear physics, radionuclide production, materials science research, nuclear technology and medicine. The Radioactive Ion Beam (RIB) produced by SPES will be accelerated by ALPI, which is a linear accelerator, equipped with superconducting quarter wave resonators (QWRs) and operating at LNL since 1990. For RIB acceleration it is mandatory to perform an upgrade of ALPI which consists of the implementation of two additional cryostats, containing 4 accelerating cavities each, in the high-ß section. The QWRs production technology is well established. The production technology of Nb/Cu QWRs should be adjusted for high-ß cavities production. In the framework of the upgrade, several vacuum systems were refurbished, optimal parameters of the biased sputtering processes of copper QWR cavities and plates were defined. The process of mechanical and chemical preparation, sputtering and cryogenic measurement of the high-ß Nb/Cu QWR cavities were adjusted. Several QWR cavities were already produced and measured. Currently, the production of the Nb/Cu sputtered QWR cavities and plates is ongoing.
	Poster SUPCAV005 [0.943 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2021-SUPCAV005
About •	Received ※ 21 June 2021 — Revised ※ 07 July 2021 — Accepted ※ 12 August 2021 — Issue date ※ 29 April 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

SUPCAV007	Thick Film Morphology and SC Characterizations of 6 GHz Nb/Cu Cavities	18
	V.A. Garcia Diaz, O. Azzolini, E. Chyhyrynets, G. Keppel, C. Pira, F. Stivanello, M. Zanierato INFN/LNL, Legnaro (PD), Italy E. Chyhyrynets Università degli Studi di Padova, Padova, Italy D. Fonnesu CERN, Meyrin, Switzerland O. Kugeler, D.B. Tikhonov HZB, Berlin, Germany R. Valizadeh STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom M. Vogel University Siegen, Siegen, Germany
	Funding: European Union’s H2020 Framework Programme under Grant Agreement no. 764879 Thick films deposited in long pulse DCMS mode onto 6 GHz copper cavities have demonstrated the mitigation of the Q-slope at low accelerating fields. The Nb thick films (~40 microns) show the possibility to reproduce the bulk niobium superconducting properties and morpholo-gy characterizations exhibited dense and void-free films that are encouraging for the scaling of the process to 1.3 GHz cavities. In this work a full characterization of thick films by DC magnetometry, computer tomography, SEM and RF characterizations are presented.
	Poster SUPCAV007 [1.012 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2021-SUPCAV007
About •	Received ※ 21 June 2021 — Revised ※ 07 July 2021 — Accepted ※ 16 February 2022 — Issue date ※ 08 April 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

SUPFDV006	Investigation of SIS Multilayer Films at HZB	72
	D.B. Tikhonov, S. Keckert, J. Knobloch, O. Kugeler HZB, Berlin, Germany E. Chyhyrynets, C. Pira INFN/LNL, Legnaro (PD), Italy J. Knobloch University of Siegen, Siegen, Germany S.B. Leith, M. Vogel University Siegen, Siegen, Germany
	Funding: The manufacture of the QPR samples received funding from the European Union’s Horizon 2020 Research and Innovation programme under Grant Agreement No 730871 The systematic study of multilayer SIS films (Superconductor-Insulator-Superconductor) is being conducted in Helmholtz-Zentrum Berlin. Such films theoretically should boost the performance of superconducting cavities, and reduce some problems related to bulk Nb such as magnetic flux trapping. Up to now such films have been presented in theory, but the RF performance of those structures have not been widely studied. In this contribution we present the results of the latest tests of AlN-NbN films, deposited on micrometers-thick Nb layers on copper. It has, also, been shown previously at HZB that such SIS films may show some unexpected behavior in surface resistance versus temperature parameter space. In this contribution we continue to investigate those effects with the variation of different parameters of films (such as insulator thickness) and production recipes.
	Poster SUPFDV006 [2.234 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2021-SUPFDV006
About •	Received ※ 21 June 2021 — Revised ※ 09 July 2021 — Accepted ※ 12 August 2021 — Issue date ※ 21 December 2021
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SUPFDV007	Magnetic Field Penetration of Niobium Thin Films Produced by the ARIES Collaboration	77
	D.A. Turner Cockcroft Institute, Lancaster University, Lancaster, United Kingdom G. Burt, K.D. Dumbell, O.B. Malyshev, R. Valizadeh Cockcroft Institute, Warrington, Cheshire, United Kingdom G. Burt Lancaster University, Lancaster, United Kingdom E. Chyhyrynets, C. Pira INFN/LNL, Legnaro (PD), Italy T. Junginger TRIUMF, Vancouver, Canada T. Junginger UVIC, Victoria, Canada S.B. Leith, M. Vogel University Siegen, Siegen, Germany O.B. Malyshev, R. Valizadeh STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom A. Medvids, P. Onufrijevs Riga Technical University, Riga, Latvia R. Ries Slovak Academy of Sciences, Institute of Electrical Engineering, Bratislava, Slovak Republic E. Seiler IEE, Bratislava, Slovak Republic A. Sublet CERN, Meyrin, Switzerland J.T.G. Wilson STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom
	Superconducting (SC) thin film coatings on Cu substrates are already widely used as an alternative to bulk Nb SRF structures. Using Cu allows improved thermal stability compared to Nb due to having a greater thermal conductivity. Niobium thin film coatings also reduce the amount of Nb required to produce a cavity. The performance of thin film Nb cavities is not as good as bulk Nb cavities. The H2020 ARIES WP15 collaboration studied the impact of substrate polishing and the effect produced on Nb thin film depositions. Multiple samples were produced from Cu and polished with various techniques. The polished Cu substrates were then coated with a Nb film at partner institutions. These samples were characterised with surface characterisation techniques for film morphology and structure. The SC properties were studied with 2 DC techniques, a vibrating sample magnetometer (VSM) and a magnetic field penetration (MFP) facility. The results conclude that both chemical polishing and electropolishing produce the best DC properties in the MFP facility. A comparison between the VSM and the MFP facility can be made for 10 micron thick samples, but not for 3 micron thick samples.
	Poster SUPFDV007 [1.064 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2021-SUPFDV007
About •	Received ※ 21 June 2021 — Accepted ※ 28 October 2021 — Issue date ※ 09 April 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

SUPTEV002	Application of Plasma Electrolytic Polishing onto SRF Substrates	116
	E. Chyhyrynets, O. Azzolini, R. Caforio, V.A. Garcia Diaz, G. Keppel, C. Pira, F. Stivanello, M. Zanierato INFN/LNL, Legnaro (PD), Italy
	Funding: Work supported by the INFN CSNV experiment TEFEN. This project has received funding from the Euro-pean Union’s Horizon 2020 Research and Innovation programme under GA No 101004730. A new promising approach of SRF substrates surface treatment has been studied - Plasma Electrolytic Polishing (PEP). The possible application of PEP can be used not only on conventional elliptical resonators, but also on other components of SRF such as, for example, couplers or Quadrupole resonators (QPRs). However, SRF application of PEP represents a challenge since it requires a different approach to treat the inner surface of elliptical cavities respect to electropolishing. In this work, the main problematics and possible solutions, the equipment, and the polishing system requirements will be shown. A proposed polishing system for 6 GHz elliptical cavities and QPRs will be shown and discussed.
	Poster SUPTEV002 [2.715 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2021-SUPTEV002
About •	Received ※ 21 June 2021 — Revised ※ 08 July 2021 — Accepted ※ 12 August 2021 — Issue date ※ 22 April 2022
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SUPTEV003	Cu/Nb QPR Surface Preparation Protocol in the Framework of ARIES Project	121
	E. Chyhyrynets, O. Azzolini, R. Caforio, V.A. Garcia Diaz, G. Keppel, C. Pira, F. Stivanello INFN/LNL, Legnaro (PD), Italy
	Funding: Work supported by the INFN CSNV experiment TEFEN. This project has received funding from the European Union’s Horizon 2020 Research and Innovation Pro-gramme under Grant Agreement no. 730871. The Quadrupole Resonator is a powerful tool for SRF R&D on thin films. It allows to perform Q vs E measurements on flat sample rather than a curved surface of a cavity. For the investigation of SC coatings on copper substrates, e-beam welded Cu/Nb samples have been prepared for the QPR. However, the presence of two metals, in particular at the interface makes proper polishing of both surfaces challenging due the different chemical behaviour of both components. In this work we present the protocol developed for surface preparation of the coexisting Cu and Nb phases and the results obtained for 5 different samples. The work was performed in the framework of the ARIES project.
	Poster SUPTEV003 [2.511 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2021-SUPTEV003
About •	Received ※ 21 June 2021 — Revised ※ 08 July 2021 — Accepted ※ 12 August 2021 — Issue date ※ 27 September 2021
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TUPCAV003	1.3 GHz Seamless Copper Cavities via CNC Spinning Technique	440
	F. Sciarrabba, O. Azzolini, G. Keppel, C. Pira INFN/LNL, Legnaro (PD), Italy I. Calliari, R. Guggia, L. Pezzato, M. Pigato UNIPD, Padova, Italy
	The spinning process is an established technology for the production of seamless resonant cavities. The main drawback is that, so far, a manual process is adopted, so the quality of the product is subject to the worker’s skills. The Compute Numerical Controlled (CNC) applied to the spinning process can be used to limit this problem and increase the reproducibility and geometrical accuracy of the cavities obtained. This work reports the first 1.3 GHz SRF seamless copper cavities produced by CNC spinning at the Laboratori Nazionali di Legnaro of INFN. For this purpose, metrological analysis were conducted to verify the geometrical accuracy of the cavities after different steps of forming and thermal treatments; axial profile and wall thickness measurements were carried out, investigating different zones of the cavity profile. The cavities were also characterized through mechanical and microstructural analysis, to identify the effect of the automatic forming process applied to the production process of the 1.3 GHz SRF seamless copper cavities.
	Poster TUPCAV003 [1.030 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2021-TUPCAV003
About •	Received ※ 21 June 2021 — Revised ※ 12 July 2021 — Accepted ※ 23 August 2021 — Issue date ※ 24 December 2021
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TUPCAV006	Nb₃Sn Films Depositions from Targets Synthesized via Liquid Tin Diffusion	452
	M. Zanierato, O. Azzolini, E. Chyhyrynets, V.A. Garcia Diaz, G. Keppel, C. Pira, F. Stivanello INFN/LNL, Legnaro (PD), Italy
	The deposition of Nb₃Sn on copper cavities is inter-esting for the higher thermal conductivity of copper compared to common Nb substrates. The better heat exchange would allow the use of cryocoolers reducing cryogenic costs and the risk of thermal quench [1]. Magnetron sputtering technology allows the deposi-tion of Nb₃Sn on substrates different than Nb, however the coating of substrates with complex geometry (such as elliptical cavities) may require targets with non-planar shape, difficult to realize with classic powder sintering techniques. In this work, the possibility of using the Liquid Tin Diffusion (LTD) technique to produce sputtering targets is explored. The LTD tech-nique is a wire fabrication technology, already devel-oped in the past at LNL for SRF applications [2], that allows the deposition of very thick and uniform coat-ing on Nb substrates even with complex geometry [3]. Improvements in LTD process, proof of concept of a single use LTD target production, and characterization of the Nb₃Sn film coated by DC magnetron sputtering with these innovative targets are reported in this work.
	Poster TUPCAV006 [5.037 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2021-TUPCAV006
About •	Received ※ 21 June 2021 — Revised ※ 12 July 2021 — Accepted ※ 23 August 2021 — Issue date ※ 02 September 2021
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WEPFDV007	Main Highlights of ARIES WP15 Collaboration	571
	O.B. Malyshev, P. Goudket, R. Valizadeh STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom C.Z. Antoine CEA-IRFU, Gif-sur-Yvette, France O. Azzolini, E. Chyhyrynets, G. Keppel, C. Pira, F. Stivanello INFN/LNL, Legnaro (PD), Italy G. Burt, D.J. Seal, D.A. Turner Cockcroft Institute, Lancaster University, Lancaster, United Kingdom G. Burt, B.S. Sian Lancaster University, Lancaster, United Kingdom O. Kugeler, D.B. Tikhonov HZB, Berlin, Germany S.B. Leith, A.Ö. Sezgin, M. Vogel University Siegen, Siegen, Germany A. Medvids, P. Onufrijevs Riga Technical University, Riga, Latvia R. Ries, E. Seiler Slovak Academy of Sciences, Institute of Electrical Engineering, Bratislava, Slovak Republic B.S. Sian Cockcroft Institute, Warrington, Cheshire, United Kingdom A. Sublet, G. Vandoni, L. Vega Cid, W. Venturini Delsolaro, P. Vidal García CERN, Meyrin, Switzerland D.A. Turner STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom
	Funding: European Commission’s ARIES collaboration H2020 Research and Innovation Programme under Grant Agreement no. 730871 An international collaboration of research teams from CEA (France), CERN (Switzerland), INFN/LNL (Italy), HZB and USI (Germany), IEE (Slovakia), RTU (Latvia) and STFC/DL (UK), are working together on better understanding of how to improve the properties of superconducting thin films (ScTF) for RF cavities. The collaboration has been formed as WP15 in the H2020 ARIES project funded by EC. The systematic study of ScTF covers: Cu substrate polishing with different techniques (EP, SUBU, EP+SUBU, tumbling, laser), Nb, NbN, Nb₃Sn and SIS film deposition and characterisation, Laser post deposition treatments, DC magnetisation characterisation, application of all obtained knowledge on polishing, deposition and characterisation, Laser post deposition treatments, DC magnetisation characterisation, application to the QPR samples for testing the films at RF conditions. The preparation, deposition and characterisation of each sample involves 3-5 partners enhancing the capability of each other and resulting in a more complete analysis of each film. The talk will give an overview of the collaborative research and will be an introduction to the detailed talks given by the team members.
	Poster WEPFDV007 [2.013 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2021-WEPFDV007
About •	Received ※ 19 June 2021 — Accepted ※ 12 February 2022 — Issue date ※ 10 April 2022
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THOTEV06	Plasma Electrolytic Polishing as a Promising Treatment Replacement of Electropolishing in the Copper and Niobium Substrate Preparation for SRF	718
	C. Pira, O. Azzolini, R. Caforio, E. Chyhyrynets, V.A. Garcia, G. Keppel, F. Stivanello INFN/LNL, Legnaro (PD), Italy
	Superconducting radio frequency (SRF) cavities performances strongly depend on the substrate preparation. Currently, the conventional protocol of SRF surface preparation includes electropolishing (EP) as the main treatment achieving low roughness, clean and non-contaminated surfaces, both for bulk Nb and Cu substrates. Harsh and non-environmentally friendly solutions are typically used: HF and H₂SO₄ mixture for Nb, and H3PO4 with Butanol mixtures for EP of Cu. This research is focused on the application of a relatively new technique "Plasma Electrolytic Polishing" (PEP) for the SRF needs. PEP technology is an evolution of EP with a list of advantages that SRF community can benefit from. PEP requires diluted salt solutions moving to a greener approach in respect to EP. PEP can in principle substitute, or completely eliminate, intermediate steps, like mechanical and/or (electro) chemical polishing. Thanks to the superior removing rate in the field (up to 3.5 µm/min of Nb, and 10 µm/min of Cu) in one single treatment roughness below 100 nm Ra has been obtained both for Nb and Cu. In the present work a proof of concept is shown on Nb and Cu planar samples.
	Slides THOTEV06 [7.202 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2021-THOTEV06
About •	Received ※ 21 June 2021 — Accepted ※ 18 October 2021 — Issue date ※ 01 May 2022
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FROFDV06	Synthesis of Nb and Alternative Superconducting Film to Nb for SRF Cavity as Single Layer	893
	R. Valizadeh, P. Goudket, A.N. Hannah, O.B. Malyshev STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom C.Z. Antoine CEA-DRF-IRFU, France C.Z. Antoine CEA-IRFU, Gif-sur-Yvette, France E. Chyhyrynets, C. Pira INFN/LNL, Legnaro (PD), Italy P. Goudket, O.B. Malyshev, D.J. Seal, B.S. Sian, D.A. Turner Cockcroft Institute, Warrington, Cheshire, United Kingdom O. Kugeler, D.B. Tikhonov HZB, Berlin, Germany S.B. Leith, A.Ö. Sezgin, M. Vogel University Siegen, Siegen, Germany A. Medvids, P. Onufrijevs Riga Technical University, Riga, Latvia D.J. Seal, B.S. Sian, D.A. Turner Lancaster University, Lancaster, United Kingdom G.B.G. Stenning STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom A. Sublet, G. Vandoni, L. Vega Cid, W. Venturini Delsolaro, P. Vidal García CERN, Meyrin, Switzerland
	"Bulk niobium (Nb) has been the material of choice for superconducting RF (SRF) cavities but for further improvement in cavity RF performance, one may have to turn to films of Nb and to other superconducting materials deposited on copper as thermal and mechanical support. Other materials known as A15, such as Nb₃Sn or V₃Si and B1 such as NbTiN and NbN are much easier to synthesise in thin films rather than being made as bulk cavity. The potential benefits of using materials other than Nb would be a higher Tc, a potentially higher critical held Hc, leading to potentially significant cryogenics cost reduction if the cavity operation temperature is 4.2 K or higher. We report on optimising deposition parameters and effect of substrate treatment prior to deposition for successful synthesising of Nb and the alternative superconducting thin film with high superconducting properties (Tc and Hsh) on flat substrates and QPR samples in single layer. The DC and RF SC properties have been tested using PPMS and QPR measurements. This work is part of the H2020 ARIES collaboration. We further report on preparation of RF cavities employing these alternative material for future cavity production."
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2021-FROFDV06
About •	Received ※ 21 June 2021 — Accepted ※ 05 January 2022 — Issue date ※ 28 April 2022
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Paper

Title

Page

Current Status of the ALPI Linac Upgrade for the SPES Facilities at INFN LNL

11

A. Tsymbaliuk, D. Bortolato, F. Chiurlotto, E. Chyhyrynets, G. Keppel, E. Munaron, C. Pira, F. Stivanello
INFN/LNL, Legnaro (PD), Italy
E. Chyhyrynets
Università degli Studi di Padova, Padova, Italy
A. Tsymbaliuk
UNIFE, Ferrara, Italy

The SPES project is based at INFN LNL and covers basic research in nuclear physics, radionuclide production, materials science research, nuclear technology and medicine. The Radioactive Ion Beam (RIB) produced by SPES will be accelerated by ALPI, which is a linear accelerator, equipped with superconducting quarter wave resonators (QWRs) and operating at LNL since 1990. For RIB acceleration it is mandatory to perform an upgrade of ALPI which consists of the implementation of two additional cryostats, containing 4 accelerating cavities each, in the high-ß section. The QWRs production technology is well established. The production technology of Nb/Cu QWRs should be adjusted for high-ß cavities production. In the framework of the upgrade, several vacuum systems were refurbished, optimal parameters of the biased sputtering processes of copper QWR cavities and plates were defined. The process of mechanical and chemical preparation, sputtering and cryogenic measurement of the high-ß Nb/Cu QWR cavities were adjusted. Several QWR cavities were already produced and measured. Currently, the production of the Nb/Cu sputtered QWR cavities and plates is ongoing.

Poster SUPCAV005 [0.943 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2021-SUPCAV005

About •

Received ※ 21 June 2021 — Revised ※ 07 July 2021 — Accepted ※ 12 August 2021 — Issue date ※ 29 April 2022

Cite •

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

SUPCAV007

Thick Film Morphology and SC Characterizations of 6 GHz Nb/Cu Cavities

18

V.A. Garcia Diaz, O. Azzolini, E. Chyhyrynets, G. Keppel, C. Pira, F. Stivanello, M. Zanierato
INFN/LNL, Legnaro (PD), Italy
E. Chyhyrynets
Università degli Studi di Padova, Padova, Italy
D. Fonnesu
CERN, Meyrin, Switzerland
O. Kugeler, D.B. Tikhonov
HZB, Berlin, Germany
R. Valizadeh
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
M. Vogel
University Siegen, Siegen, Germany

Funding: European Union’s H2020 Framework Programme under Grant Agreement no. 764879
Thick films deposited in long pulse DCMS mode onto 6 GHz copper cavities have demonstrated the mitigation of the Q-slope at low accelerating fields. The Nb thick films (~40 microns) show the possibility to reproduce the bulk niobium superconducting properties and morpholo-gy characterizations exhibited dense and void-free films that are encouraging for the scaling of the process to 1.3 GHz cavities. In this work a full characterization of thick films by DC magnetometry, computer tomography, SEM and RF characterizations are presented.

Poster SUPCAV007 [1.012 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2021-SUPCAV007

About •

Received ※ 21 June 2021 — Revised ※ 07 July 2021 — Accepted ※ 16 February 2022 — Issue date ※ 08 April 2022

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

SUPFDV006

Investigation of SIS Multilayer Films at HZB

72

D.B. Tikhonov, S. Keckert, J. Knobloch, O. Kugeler
HZB, Berlin, Germany
E. Chyhyrynets, C. Pira
INFN/LNL, Legnaro (PD), Italy
J. Knobloch
University of Siegen, Siegen, Germany
S.B. Leith, M. Vogel
University Siegen, Siegen, Germany

Funding: The manufacture of the QPR samples received funding from the European Union’s Horizon 2020 Research and Innovation programme under Grant Agreement No 730871
The systematic study of multilayer SIS films (Superconductor-Insulator-Superconductor) is being conducted in Helmholtz-Zentrum Berlin. Such films theoretically should boost the performance of superconducting cavities, and reduce some problems related to bulk Nb such as magnetic flux trapping. Up to now such films have been presented in theory, but the RF performance of those structures have not been widely studied. In this contribution we present the results of the latest tests of AlN-NbN films, deposited on micrometers-thick Nb layers on copper. It has, also, been shown previously at HZB that such SIS films may show some unexpected behavior in surface resistance versus temperature parameter space. In this contribution we continue to investigate those effects with the variation of different parameters of films (such as insulator thickness) and production recipes.

Poster SUPFDV006 [2.234 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2021-SUPFDV006

About •

Received ※ 21 June 2021 — Revised ※ 09 July 2021 — Accepted ※ 12 August 2021 — Issue date ※ 21 December 2021

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SUPFDV007

Magnetic Field Penetration of Niobium Thin Films Produced by the ARIES Collaboration

77

D.A. Turner
Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
G. Burt, K.D. Dumbell, O.B. Malyshev, R. Valizadeh
Cockcroft Institute, Warrington, Cheshire, United Kingdom
G. Burt
Lancaster University, Lancaster, United Kingdom
E. Chyhyrynets, C. Pira
INFN/LNL, Legnaro (PD), Italy
T. Junginger
TRIUMF, Vancouver, Canada
T. Junginger
UVIC, Victoria, Canada
S.B. Leith, M. Vogel
University Siegen, Siegen, Germany
O.B. Malyshev, R. Valizadeh
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
A. Medvids, P. Onufrijevs
Riga Technical University, Riga, Latvia
R. Ries
Slovak Academy of Sciences, Institute of Electrical Engineering, Bratislava, Slovak Republic
E. Seiler
IEE, Bratislava, Slovak Republic
A. Sublet
CERN, Meyrin, Switzerland
J.T.G. Wilson
STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom

Superconducting (SC) thin film coatings on Cu substrates are already widely used as an alternative to bulk Nb SRF structures. Using Cu allows improved thermal stability compared to Nb due to having a greater thermal conductivity. Niobium thin film coatings also reduce the amount of Nb required to produce a cavity. The performance of thin film Nb cavities is not as good as bulk Nb cavities. The H2020 ARIES WP15 collaboration studied the impact of substrate polishing and the effect produced on Nb thin film depositions. Multiple samples were produced from Cu and polished with various techniques. The polished Cu substrates were then coated with a Nb film at partner institutions. These samples were characterised with surface characterisation techniques for film morphology and structure. The SC properties were studied with 2 DC techniques, a vibrating sample magnetometer (VSM) and a magnetic field penetration (MFP) facility. The results conclude that both chemical polishing and electropolishing produce the best DC properties in the MFP facility. A comparison between the VSM and the MFP facility can be made for 10 micron thick samples, but not for 3 micron thick samples.

Poster SUPFDV007 [1.064 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2021-SUPFDV007

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Received ※ 21 June 2021 — Accepted ※ 28 October 2021 — Issue date ※ 09 April 2022

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

SUPTEV002

Application of Plasma Electrolytic Polishing onto SRF Substrates

116

E. Chyhyrynets, O. Azzolini, R. Caforio, V.A. Garcia Diaz, G. Keppel, C. Pira, F. Stivanello, M. Zanierato
INFN/LNL, Legnaro (PD), Italy

Funding: Work supported by the INFN CSNV experiment TEFEN. This project has received funding from the Euro-pean Union’s Horizon 2020 Research and Innovation programme under GA No 101004730.
A new promising approach of SRF substrates surface treatment has been studied - Plasma Electrolytic Polishing (PEP). The possible application of PEP can be used not only on conventional elliptical resonators, but also on other components of SRF such as, for example, couplers or Quadrupole resonators (QPRs). However, SRF application of PEP represents a challenge since it requires a different approach to treat the inner surface of elliptical cavities respect to electropolishing. In this work, the main problematics and possible solutions, the equipment, and the polishing system requirements will be shown. A proposed polishing system for 6 GHz elliptical cavities and QPRs will be shown and discussed.

Poster SUPTEV002 [2.715 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2021-SUPTEV002

About •

Received ※ 21 June 2021 — Revised ※ 08 July 2021 — Accepted ※ 12 August 2021 — Issue date ※ 22 April 2022

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SUPTEV003

Cu/Nb QPR Surface Preparation Protocol in the Framework of ARIES Project

121

E. Chyhyrynets, O. Azzolini, R. Caforio, V.A. Garcia Diaz, G. Keppel, C. Pira, F. Stivanello
INFN/LNL, Legnaro (PD), Italy

Funding: Work supported by the INFN CSNV experiment TEFEN. This project has received funding from the European Union’s Horizon 2020 Research and Innovation Pro-gramme under Grant Agreement no. 730871.
The Quadrupole Resonator is a powerful tool for SRF R&D on thin films. It allows to perform Q vs E measurements on flat sample rather than a curved surface of a cavity. For the investigation of SC coatings on copper substrates, e-beam welded Cu/Nb samples have been prepared for the QPR. However, the presence of two metals, in particular at the interface makes proper polishing of both surfaces challenging due the different chemical behaviour of both components. In this work we present the protocol developed for surface preparation of the coexisting Cu and Nb phases and the results obtained for 5 different samples. The work was performed in the framework of the ARIES project.

Poster SUPTEV003 [2.511 MB]

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reference for this paper ※ doi:10.18429/JACoW-SRF2021-SUPTEV003

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Received ※ 21 June 2021 — Revised ※ 08 July 2021 — Accepted ※ 12 August 2021 — Issue date ※ 27 September 2021

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TUPCAV003

1.3 GHz Seamless Copper Cavities via CNC Spinning Technique

440

F. Sciarrabba, O. Azzolini, G. Keppel, C. Pira
INFN/LNL, Legnaro (PD), Italy
I. Calliari, R. Guggia, L. Pezzato, M. Pigato
UNIPD, Padova, Italy

The spinning process is an established technology for the production of seamless resonant cavities. The main drawback is that, so far, a manual process is adopted, so the quality of the product is subject to the worker’s skills. The Compute Numerical Controlled (CNC) applied to the spinning process can be used to limit this problem and increase the reproducibility and geometrical accuracy of the cavities obtained. This work reports the first 1.3 GHz SRF seamless copper cavities produced by CNC spinning at the Laboratori Nazionali di Legnaro of INFN. For this purpose, metrological analysis were conducted to verify the geometrical accuracy of the cavities after different steps of forming and thermal treatments; axial profile and wall thickness measurements were carried out, investigating different zones of the cavity profile. The cavities were also characterized through mechanical and microstructural analysis, to identify the effect of the automatic forming process applied to the production process of the 1.3 GHz SRF seamless copper cavities.

Poster TUPCAV003 [1.030 MB]

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reference for this paper ※ doi:10.18429/JACoW-SRF2021-TUPCAV003

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Received ※ 21 June 2021 — Revised ※ 12 July 2021 — Accepted ※ 23 August 2021 — Issue date ※ 24 December 2021

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TUPCAV006

Nb₃Sn Films Depositions from Targets Synthesized via Liquid Tin Diffusion

452

M. Zanierato, O. Azzolini, E. Chyhyrynets, V.A. Garcia Diaz, G. Keppel, C. Pira, F. Stivanello
INFN/LNL, Legnaro (PD), Italy

The deposition of Nb₃Sn on copper cavities is inter-esting for the higher thermal conductivity of copper compared to common Nb substrates. The better heat exchange would allow the use of cryocoolers reducing cryogenic costs and the risk of thermal quench [1]. Magnetron sputtering technology allows the deposi-tion of Nb₃Sn on substrates different than Nb, however the coating of substrates with complex geometry (such as elliptical cavities) may require targets with non-planar shape, difficult to realize with classic powder sintering techniques. In this work, the possibility of using the Liquid Tin Diffusion (LTD) technique to produce sputtering targets is explored. The LTD tech-nique is a wire fabrication technology, already devel-oped in the past at LNL for SRF applications [2], that allows the deposition of very thick and uniform coat-ing on Nb substrates even with complex geometry [3]. Improvements in LTD process, proof of concept of a single use LTD target production, and characterization of the Nb₃Sn film coated by DC magnetron sputtering with these innovative targets are reported in this work.

Poster TUPCAV006 [5.037 MB]

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reference for this paper ※ doi:10.18429/JACoW-SRF2021-TUPCAV006

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Received ※ 21 June 2021 — Revised ※ 12 July 2021 — Accepted ※ 23 August 2021 — Issue date ※ 02 September 2021

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WEPFDV007

Main Highlights of ARIES WP15 Collaboration

571

O.B. Malyshev, P. Goudket, R. Valizadeh
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
C.Z. Antoine
CEA-IRFU, Gif-sur-Yvette, France
O. Azzolini, E. Chyhyrynets, G. Keppel, C. Pira, F. Stivanello
INFN/LNL, Legnaro (PD), Italy
G. Burt, D.J. Seal, D.A. Turner
Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
G. Burt, B.S. Sian
Lancaster University, Lancaster, United Kingdom
O. Kugeler, D.B. Tikhonov
HZB, Berlin, Germany
S.B. Leith, A.Ö. Sezgin, M. Vogel
University Siegen, Siegen, Germany
A. Medvids, P. Onufrijevs
Riga Technical University, Riga, Latvia
R. Ries, E. Seiler
Slovak Academy of Sciences, Institute of Electrical Engineering, Bratislava, Slovak Republic
B.S. Sian
Cockcroft Institute, Warrington, Cheshire, United Kingdom
A. Sublet, G. Vandoni, L. Vega Cid, W. Venturini Delsolaro, P. Vidal García
CERN, Meyrin, Switzerland
D.A. Turner
STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom

Funding: European Commission’s ARIES collaboration H2020 Research and Innovation Programme under Grant Agreement no. 730871
An international collaboration of research teams from CEA (France), CERN (Switzerland), INFN/LNL (Italy), HZB and USI (Germany), IEE (Slovakia), RTU (Latvia) and STFC/DL (UK), are working together on better understanding of how to improve the properties of superconducting thin films (ScTF) for RF cavities. The collaboration has been formed as WP15 in the H2020 ARIES project funded by EC. The systematic study of ScTF covers: Cu substrate polishing with different techniques (EP, SUBU, EP+SUBU, tumbling, laser), Nb, NbN, Nb₃Sn and SIS film deposition and characterisation, Laser post deposition treatments, DC magnetisation characterisation, application of all obtained knowledge on polishing, deposition and characterisation, Laser post deposition treatments, DC magnetisation characterisation, application to the QPR samples for testing the films at RF conditions. The preparation, deposition and characterisation of each sample involves 3-5 partners enhancing the capability of each other and resulting in a more complete analysis of each film. The talk will give an overview of the collaborative research and will be an introduction to the detailed talks given by the team members.

Poster WEPFDV007 [2.013 MB]

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reference for this paper ※ doi:10.18429/JACoW-SRF2021-WEPFDV007

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Received ※ 19 June 2021 — Accepted ※ 12 February 2022 — Issue date ※ 10 April 2022

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THOTEV06

Plasma Electrolytic Polishing as a Promising Treatment Replacement of Electropolishing in the Copper and Niobium Substrate Preparation for SRF

718

C. Pira, O. Azzolini, R. Caforio, E. Chyhyrynets, V.A. Garcia, G. Keppel, F. Stivanello
INFN/LNL, Legnaro (PD), Italy

Superconducting radio frequency (SRF) cavities performances strongly depend on the substrate preparation. Currently, the conventional protocol of SRF surface preparation includes electropolishing (EP) as the main treatment achieving low roughness, clean and non-contaminated surfaces, both for bulk Nb and Cu substrates. Harsh and non-environmentally friendly solutions are typically used: HF and H₂SO₄ mixture for Nb, and H3PO4 with Butanol mixtures for EP of Cu. This research is focused on the application of a relatively new technique "Plasma Electrolytic Polishing" (PEP) for the SRF needs. PEP technology is an evolution of EP with a list of advantages that SRF community can benefit from. PEP requires diluted salt solutions moving to a greener approach in respect to EP. PEP can in principle substitute, or completely eliminate, intermediate steps, like mechanical and/or (electro) chemical polishing. Thanks to the superior removing rate in the field (up to 3.5 µm/min of Nb, and 10 µm/min of Cu) in one single treatment roughness below 100 nm Ra has been obtained both for Nb and Cu. In the present work a proof of concept is shown on Nb and Cu planar samples.

Slides THOTEV06 [7.202 MB]

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reference for this paper ※ doi:10.18429/JACoW-SRF2021-THOTEV06

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Received ※ 21 June 2021 — Accepted ※ 18 October 2021 — Issue date ※ 01 May 2022

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FROFDV06

Synthesis of Nb and Alternative Superconducting Film to Nb for SRF Cavity as Single Layer

893

R. Valizadeh, P. Goudket, A.N. Hannah, O.B. Malyshev
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
C.Z. Antoine
CEA-DRF-IRFU, France
C.Z. Antoine
CEA-IRFU, Gif-sur-Yvette, France
E. Chyhyrynets, C. Pira
INFN/LNL, Legnaro (PD), Italy
P. Goudket, O.B. Malyshev, D.J. Seal, B.S. Sian, D.A. Turner
Cockcroft Institute, Warrington, Cheshire, United Kingdom
O. Kugeler, D.B. Tikhonov
HZB, Berlin, Germany
S.B. Leith, A.Ö. Sezgin, M. Vogel
University Siegen, Siegen, Germany
A. Medvids, P. Onufrijevs
Riga Technical University, Riga, Latvia
D.J. Seal, B.S. Sian, D.A. Turner
Lancaster University, Lancaster, United Kingdom
G.B.G. Stenning
STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom
A. Sublet, G. Vandoni, L. Vega Cid, W. Venturini Delsolaro, P. Vidal García
CERN, Meyrin, Switzerland

"Bulk niobium (Nb) has been the material of choice for superconducting RF (SRF) cavities but for further improvement in cavity RF performance, one may have to turn to films of Nb and to other superconducting materials deposited on copper as thermal and mechanical support. Other materials known as A15, such as Nb₃Sn or V₃Si and B1 such as NbTiN and NbN are much easier to synthesise in thin films rather than being made as bulk cavity. The potential benefits of using materials other than Nb would be a higher Tc, a potentially higher critical held Hc, leading to potentially significant cryogenics cost reduction if the cavity operation temperature is 4.2 K or higher. We report on optimising deposition parameters and effect of substrate treatment prior to deposition for successful synthesising of Nb and the alternative superconducting thin film with high superconducting properties (Tc and Hsh) on flat substrates and QPR samples in single layer. The DC and RF SC properties have been tested using PPMS and QPR measurements. This work is part of the H2020 ARIES collaboration. We further report on preparation of RF cavities employing these alternative material for future cavity production."

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reference for this paper ※ doi:10.18429/JACoW-SRF2021-FROFDV06

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Received ※ 21 June 2021 — Accepted ※ 05 January 2022 — Issue date ※ 28 April 2022

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