SRF2021 - List of Keywords (lattice)

Paper	Title	Other Keywords	Page
SUPFDV012	The Development of HiPIMS Multilayer SIS Film Coatings on Copper for SRF Applications	site, cavity, SRF, shielding	86
	S.B. Leith, X. Jiang, A.O. Sezgin, M. Vogel University Siegen, Siegen, Germany B. Butz, Y. Li, J. Müller MNaF, Siegen, Germany S. Keckert, J. Knobloch, O. Kugeler, D.B. Tikhonov HZB, Berlin, Germany J. Knobloch University of Siegen, Siegen, Germany R. Ries, E. Seiler Slovak Academy of Sciences, Institute of Electrical Engineering, Bratislava, Slovak Republic
	Funding: Authors acknowledge both the EASITrain, Marie Sklodowska-Curie Action (MSCA) Innovative Training Network (ITN), Grant Agreement no. 764879 and the ARIES collaboration, Grant Agreement no. 730871 In recent years, the use of alternatives to bulk Nb in the fabrication of SRF cavities, including novel materials and/or fabrication techniques, have been extensively explored by the SRF community. One of these new methodologies is the use of a superconductor-insulator-superconductor (SIS) multilayer structure. Typically, these have been envisaged for use with bulk Nb cavities. However, it is conceivable to combine the benefits of SIS structures with the benefits of coated Cu cavities. It is also clear that the use of energetic deposition techniques such as high power impulse magnetron sputtering (HiPIMS), provide significant benefits over typical DC magnetron sputtering (MS) coatings, in terms of SRF performance. In light of this, two series of multilayer SIS film coatings, with a Nb-AlN-NbN structure, were deposited onto electropolished OFHC Cu samples, with the use of HiPIMS, in order to determine the efficacy of this approach. This contribution details the development of these coatings and the required optimization of the coating parameters of the separate material systems, through the use of multiple material and superconducting characterization techniques.
	Poster SUPFDV012 [2.061 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2021-SUPFDV012
About •	Received ※ 20 June 2021 — Accepted ※ 21 December 2021 — Issue date ※ 27 April 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

SUPFDV013	HiPIMS NbN Thin Film Development for Use in Multilayer SIS Films	site, cathode, ECR, cavity	91
	S.B. Leith, B. Bai, X. Jiang, M. Vogel University Siegen, Siegen, Germany R. Ries, E. Seiler Slovak Academy of Sciences, Institute of Electrical Engineering, Bratislava, Slovak Republic
	Funding: Authors acknowledge both the EASITrain, Marie Sklodowska-Curie Action (MSCA) Innovative Training Network (ITN), Grant Agreement no. 764879 and the ARIES collaboration, Grant Agreement no. 730871 As part of efforts to improve the performance of SRF cavities, the use of alternative structures, such as superconductor-insulator-superconductor (SIS) film coatings have been extensively investigated. Initial efforts using DC magnetron sputtering (MS) deposited NbN films showed the efficacy of this approach. The use of energetic condensation methods, such as high power impulse magnetron sputtering (HiPIMS), have already improved the performance of Nb thin films for SRF cavities and have already been used for nitride film coatings in the tool industry. In this contribution, the results from the deposition of HiPIMS NbN thin films onto oxygen free high conductivity (OFHC) Cu substrates are presented. The effects of the different deposition parameters on the deposited films were elucidated through various characterisation methods, resulting in an optimum coating procedure. This allowed for further comparison between the HiPIMS NbN films and the previously presented DC MS NbN films. The results indicate the improvements offered by HiPIMS deposition, most notably, the significant increase in the entry field, and its applicability to the deposition of SIS films on Cu.
	Poster SUPFDV013 [0.923 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2021-SUPFDV013
About •	Received ※ 20 June 2021 — Revised ※ 08 July 2021 — Accepted ※ 12 August 2021 — Issue date ※ 25 October 2021
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPFDV010	Microstructure Changes Observed in the Near-Surface Region of SRF Nb Cavities Cutouts upon Cooling/Heating Cycles Using GI-Synchrotron XRD	site, cavity, SRF, niobium	339
	A. Cano, D. Bafia, A. Grassellino, J. Lee, M. Martinello, A.S. Romanenko, T. Spina, Z-H. Sung Fermilab, Batavia, Illinois, USA E.A. Karapetrova ANL, Lemont, Illinois, USA
	We have mapped microstructural changes in the near-surface region of Nb from SRF cavity-cutouts upon thermal cycles in the range from 300 to 30 K using grazing incidence synchrotron X-Ray diffraction (GIXRD). Segregation of secondary phases was observed after the thermal cycle, and their nature has been clarified and discussed in view of previous studies on hydrides formation in SRF bulk Nb cavities. The temperature dependence of the relative population of these formed phases was obtained from GIXRD patterns profile fitting. Both, Nb bulk matrix and the new phases formed after cool-down show specific structural features as thermal contraction/expansion, structural transitions, and Nb lattice variation due to the induced strain by precipitates formation. The information derived from this structural study can explain some phenomena as the dissipation at high accelerating field (i.e. High Field Q Slope, HFQS) in the Nb SRF performance as well as new mechanisms never addressed in previous studies. A Romanenko, F Barkov, LD Cooley, A Grassellino, Proximity breakdown of hydrides in superconducting niobium cavities, Superconductor Science and Technology, 2013
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2021-MOPFDV010
About •	Received ※ 28 June 2021 — Revised ※ 12 August 2021 — Accepted ※ 21 August 2021 — Issue date ※ 23 September 2021
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUOFDV03	Vacancy-Hydrogen Dynamics and Magnetic Impurities During Mid-T Bake	cavity, niobium, interface, positron	342
	M. Wenskat, C. Bate, D. Reschke, J. Schaffran, L. Steder, H. Weise DESY, Hamburg, Germany C. Bate, G.D.L. Semione, A. Stierle University of Hamburg, Hamburg, Germany M. Butterling, E. Hirschmann, M.O. Liedke, A. Wagner HZDR, Dresden, Germany J. Cizek Charles University, Prague, Czech Republic W. Hillert University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany
	Positron annihilation measurements allow to study the hydrogen interaction with vacancies in a crystal lattice. Furthermore, the 3/2 ratio of the positronium annihilation can be used to identify local magnetic impurities in thin layers. Dynamic studies of these properties in annealing studies up to 300°C will be presented. The discussion is accompanied by X-ray reflectivity studies performed on single crystal samples to study the niobium oxide dissolution. The dynamics of magnetic impurities during a Mid-T bake will be presented, put into the context of cavity studies and a potential link to rf properties will be discussed.
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2021-TUOFDV03
About •	Received ※ 23 June 2021 — Revised ※ 12 July 2021 — Accepted ※ 21 August 2021 — Issue date ※ 05 December 2021
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPFDV002	The Influence of Irradiation on the Current Carrying Phenomena in HTc Multilayered Superconductors	induction, radiation, ECR, neutron	756
	J. Sosnowski NCBJ, Świerk/Otwock, Poland
	Paper is devoted to analysis of the influence of irradiation arising in SRF accelerators on critical current phenomena of HTc multilayered superconductors. Impact of size and concentration of created then nano-defects on current-voltage characteristics and critical current of HTc superconductors as function of the magnetic field and temperature will be investigated. It will be studied basing on analysis of interaction of the magnetic pancake vortices with arising during irradiation defects, for various strengths of capturing. The comparison of the model with experimental data will be given too. The dynamic losses dependent on critical current, generated in the superconducting current leads for varying current, will be considered. Analysis of the dynamic magnetic induction distribution inside superconducting lead for time varying current in the cycle will be given and Joule losses estimated. As the result it has been established the hysteresis behavior of the losses in current leads. The changes of losses have been observed for first and following current increase, which effect should have meaning during multiply charging of the superconducting electromagnets.
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2021-THPFDV002
About •	Received ※ 16 June 2021 — Revised ※ 10 August 2021 — Accepted ※ 23 November 2021 — Issue date ※ 02 March 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

Paper

Title

Other Keywords

Page

SUPFDV012

The Development of HiPIMS Multilayer SIS Film Coatings on Copper for SRF Applications

site, cavity, SRF, shielding

86

S.B. Leith, X. Jiang, A.O. Sezgin, M. Vogel
University Siegen, Siegen, Germany
B. Butz, Y. Li, J. Müller
MNaF, Siegen, Germany
S. Keckert, J. Knobloch, O. Kugeler, D.B. Tikhonov
HZB, Berlin, Germany
J. Knobloch
University of Siegen, Siegen, Germany
R. Ries, E. Seiler
Slovak Academy of Sciences, Institute of Electrical Engineering, Bratislava, Slovak Republic

Funding: Authors acknowledge both the EASITrain, Marie Sklodowska-Curie Action (MSCA) Innovative Training Network (ITN), Grant Agreement no. 764879 and the ARIES collaboration, Grant Agreement no. 730871
In recent years, the use of alternatives to bulk Nb in the fabrication of SRF cavities, including novel materials and/or fabrication techniques, have been extensively explored by the SRF community. One of these new methodologies is the use of a superconductor-insulator-superconductor (SIS) multilayer structure. Typically, these have been envisaged for use with bulk Nb cavities. However, it is conceivable to combine the benefits of SIS structures with the benefits of coated Cu cavities. It is also clear that the use of energetic deposition techniques such as high power impulse magnetron sputtering (HiPIMS), provide significant benefits over typical DC magnetron sputtering (MS) coatings, in terms of SRF performance. In light of this, two series of multilayer SIS film coatings, with a Nb-AlN-NbN structure, were deposited onto electropolished OFHC Cu samples, with the use of HiPIMS, in order to determine the efficacy of this approach. This contribution details the development of these coatings and the required optimization of the coating parameters of the separate material systems, through the use of multiple material and superconducting characterization techniques.

Poster SUPFDV012 [2.061 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2021-SUPFDV012

About •

Received ※ 20 June 2021 — Accepted ※ 21 December 2021 — Issue date ※ 27 April 2022

Cite •

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

SUPFDV013

HiPIMS NbN Thin Film Development for Use in Multilayer SIS Films

site, cathode, ECR, cavity

91

S.B. Leith, B. Bai, X. Jiang, M. Vogel
University Siegen, Siegen, Germany
R. Ries, E. Seiler
Slovak Academy of Sciences, Institute of Electrical Engineering, Bratislava, Slovak Republic

Funding: Authors acknowledge both the EASITrain, Marie Sklodowska-Curie Action (MSCA) Innovative Training Network (ITN), Grant Agreement no. 764879 and the ARIES collaboration, Grant Agreement no. 730871
As part of efforts to improve the performance of SRF cavities, the use of alternative structures, such as superconductor-insulator-superconductor (SIS) film coatings have been extensively investigated. Initial efforts using DC magnetron sputtering (MS) deposited NbN films showed the efficacy of this approach. The use of energetic condensation methods, such as high power impulse magnetron sputtering (HiPIMS), have already improved the performance of Nb thin films for SRF cavities and have already been used for nitride film coatings in the tool industry. In this contribution, the results from the deposition of HiPIMS NbN thin films onto oxygen free high conductivity (OFHC) Cu substrates are presented. The effects of the different deposition parameters on the deposited films were elucidated through various characterisation methods, resulting in an optimum coating procedure. This allowed for further comparison between the HiPIMS NbN films and the previously presented DC MS NbN films. The results indicate the improvements offered by HiPIMS deposition, most notably, the significant increase in the entry field, and its applicability to the deposition of SIS films on Cu.

Poster SUPFDV013 [0.923 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2021-SUPFDV013

About •

Received ※ 20 June 2021 — Revised ※ 08 July 2021 — Accepted ※ 12 August 2021 — Issue date ※ 25 October 2021

Cite •

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

MOPFDV010

Microstructure Changes Observed in the Near-Surface Region of SRF Nb Cavities Cutouts upon Cooling/Heating Cycles Using GI-Synchrotron XRD

site, cavity, SRF, niobium

339

A. Cano, D. Bafia, A. Grassellino, J. Lee, M. Martinello, A.S. Romanenko, T. Spina, Z-H. Sung
Fermilab, Batavia, Illinois, USA
E.A. Karapetrova
ANL, Lemont, Illinois, USA

We have mapped microstructural changes in the near-surface region of Nb from SRF cavity-cutouts upon thermal cycles in the range from 300 to 30 K using grazing incidence synchrotron X-Ray diffraction (GIXRD). Segregation of secondary phases was observed after the thermal cycle, and their nature has been clarified and discussed in view of previous studies on hydrides formation in SRF bulk Nb cavities. The temperature dependence of the relative population of these formed phases was obtained from GIXRD patterns profile fitting. Both, Nb bulk matrix and the new phases formed after cool-down show specific structural features as thermal contraction/expansion, structural transitions, and Nb lattice variation due to the induced strain by precipitates formation. The information derived from this structural study can explain some phenomena as the dissipation at high accelerating field (i.e. High Field Q Slope, HFQS) in the Nb SRF performance as well as new mechanisms never addressed in previous studies.
A Romanenko, F Barkov, LD Cooley, A Grassellino, Proximity breakdown of hydrides in superconducting niobium cavities, Superconductor Science and Technology, 2013

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2021-MOPFDV010

About •

Received ※ 28 June 2021 — Revised ※ 12 August 2021 — Accepted ※ 21 August 2021 — Issue date ※ 23 September 2021

Cite •

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

TUOFDV03

Vacancy-Hydrogen Dynamics and Magnetic Impurities During Mid-T Bake

cavity, niobium, interface, positron

342

M. Wenskat, C. Bate, D. Reschke, J. Schaffran, L. Steder, H. Weise
DESY, Hamburg, Germany
C. Bate, G.D.L. Semione, A. Stierle
University of Hamburg, Hamburg, Germany
M. Butterling, E. Hirschmann, M.O. Liedke, A. Wagner
HZDR, Dresden, Germany
J. Cizek
Charles University, Prague, Czech Republic
W. Hillert
University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany

Positron annihilation measurements allow to study the hydrogen interaction with vacancies in a crystal lattice. Furthermore, the 3/2 ratio of the positronium annihilation can be used to identify local magnetic impurities in thin layers. Dynamic studies of these properties in annealing studies up to 300°C will be presented. The discussion is accompanied by X-ray reflectivity studies performed on single crystal samples to study the niobium oxide dissolution. The dynamics of magnetic impurities during a Mid-T bake will be presented, put into the context of cavity studies and a potential link to rf properties will be discussed.

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2021-TUOFDV03

About •

Received ※ 23 June 2021 — Revised ※ 12 July 2021 — Accepted ※ 21 August 2021 — Issue date ※ 05 December 2021

Cite •

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

THPFDV002

The Influence of Irradiation on the Current Carrying Phenomena in HTc Multilayered Superconductors

induction, radiation, ECR, neutron

756

J. Sosnowski
NCBJ, Świerk/Otwock, Poland

Paper is devoted to analysis of the influence of irradiation arising in SRF accelerators on critical current phenomena of HTc multilayered superconductors. Impact of size and concentration of created then nano-defects on current-voltage characteristics and critical current of HTc superconductors as function of the magnetic field and temperature will be investigated. It will be studied basing on analysis of interaction of the magnetic pancake vortices with arising during irradiation defects, for various strengths of capturing. The comparison of the model with experimental data will be given too. The dynamic losses dependent on critical current, generated in the superconducting current leads for varying current, will be considered. Analysis of the dynamic magnetic induction distribution inside superconducting lead for time varying current in the cycle will be given and Joule losses estimated. As the result it has been established the hysteresis behavior of the losses in current leads. The changes of losses have been observed for first and following current increase, which effect should have meaning during multiply charging of the superconducting electromagnets.

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2021-THPFDV002

About •

Received ※ 16 June 2021 — Revised ※ 10 August 2021 — Accepted ※ 23 November 2021 — Issue date ※ 02 March 2022

Cite •

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