SRF2017 - List of Authors (Junginger, T.)

Paper	Title	Page
WEXA05	Dirty Layers, Bi-layers and Multi-layers: Insights from Muon Spin Rotation Experiments
	T. Junginger, R.E. Laxdal, D.W. Storey, E. Thoeng TRIUMF, Vancouver, Canada D.L. Hall, M. Liepe Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA T. Junginger HZB, Berlin, Germany S. Posen Fermilab, Batavia, Illinois, USA T. Prokscha, Z. Salman, A. Suter PSI, Villigen PSI, Switzerland D.W. Storey Victoria University, Victoria, B.C., Canada T. Tan, W.K. Withanage, M.A. Wolak, X. Xi Temple University, Philadelphia, USA E. Thoeng UBC & TRIUMF, Vancouver, British Columbia, Canada A-M. Valente-Feliciano JLab, Newport News, Virginia, USA W.W. Wasserman UBC, Vancouver, B.C., Canada
	Funding: This research was supported by a Marie Curie International Outgoing Fellowship within the EU Seventh Framework Programme for Research and Technological Development (2007-2013). The multilayer approach is being investigated for SRF applications since 2006 "". More recently the option of using a bilayer system of two superconductors has been considered as an alternative approach to reach accelerating gradients beyond bulk niobium or to explain the gradient enhancement from a 120°C bake by introduction of a 'dirty layer ""'. In this talk results are presented from two muon spin rotation experiments at TRIUMF and PSI. The former measures the field of first entry Hentry. It will be shown that MgB2 and Nb3Sn on top of Nb both push Hentry above Hc1 to a value consistent with Hsh, independent of the layer thickness. 120°C baking increases Hentry slightly but significantly above Hc1. Using the low energy muon beam at PSI we show that there is a long range proximity effect in a bilayer system of NbTiN on Nb. This effect yields a stronger decay of the RF field with depth as expected for pure NbTiN, opposite to what has been predicted for a bi-layer system due to counter current flow at the superconductor-superconductor interface "*". An insulating layer suppresses this proximity effect. Gurevich, A. APL 88.1 (2006) Checchin, M. Diss. Illinois Institute of Technology, 2016. Kubo, T. Superconductor Science and Technology 30.2 (2016) * Kubo, T et al. APL 104.3 (2014)
	Slides WEXA05 [3.716 MB]
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THPB017	Investigation of Trapped Magnetic Flux in Superconducting Niobium Samples with Neutron Radiography	762
	O. Kugeler, T. Junginger, J. Knobloch, M.M. Krzyzagorski, J.M. Köszegi, L. Riik, W. Treimer, R.F. Ziesche HZB, Berlin, Germany
	The dynamics of flux expulsion in Nb samples during superconducting transition has been investigated with neutron radiography. Aiming at a reduction of the trapped flux with respect to obtaining a small residual resistance it was attempted to influence the expulsion by applying external AC magnetic fields. The results of these experiments are presented.
	Poster THPB017 [1.528 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-THPB017
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MOPB042	The TRIUMF/VECC Injector Cryomodule Performance	144
	Y. Ma, K. Fong, T. Junginger, D. Kishi, A.N. Koveshnikov, R.E. Laxdal, N. Muller, R.R. Nagimov, D.W. Storey, E. Thoeng, Z.Y. Yao, V. Zvyagintsev TRIUMF, Vancouver, Canada U. Bhunia, A. Chakrabarti, S. Dechoudhury, V. Naik VECC, Kolkata, India
	The collaboration on superconducting electron Linac for rare ion beam facilities ARIEL (Advanced Rare Iso-topE Laboratory) [1-4] and ANURIB [5] (Advanced Na-tional facility for Unstable and Rare Isotope Beams) has resulted in production of a superconducting Injector Cryomodule (VECC ICM) at TRIUMF for VECC. The cryomodule design utilizes a unique box cryomodule with a top-loading cold mass. The hermetic unit consists of a niobium cavity which operating at 1.3GHz and connected with two symmetrically opposed couplers which can deliver 100kW RF power to the beam. Liquid helium supplied at 4.4 K is converted to superfluid helium-II through a cryogenic insert on board which includes 4 K phase separator, 4K/2K heat exchanger and Joule-Thompson valve. In 2016, the VECC ICM has been tested at TRIUMF and demonstrated 10.5 MeV acceleration. A summary of the VECC ICM commissioning are presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-MOPB042
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TUPB064	Operating Experience on Cavity Performance of ISAC-II Superconducting Heavy Ion Linac	527
	Z.Y. Yao, T. Junginger, A.N. Koveshnikov, R.E. Laxdal, Y. Ma, D.W. Storey, E. Thoeng, B.S. Waraich, V. Zvyagintsev TRIUMF, Vancouver, Canada
	ISAC-II is a superconducting heavy ion linac with 40 QWRs as an extension of ISAC facility for ISOL based on radioactive ion beam production and acceleration. Phase-I with twenty 106MHz cavities has been operating since 2006. The design spec was achieved with the completion of Phase-II with another twenty 141MHz cavities in 2010. The cavity performance statistics and operating experience have been accumulated over years. This paper will summarize the operating experience on cavity performance of ISAC-II.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-TUPB064
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TUPB065	Design of Multi-frequency Coaxial Test Resonators	531
	Z.Y. Yao, T. Junginger, R.E. Laxdal, B. Matheson, B.S. Waraich, V. Zvyagintsev TRIUMF, Vancouver, Canada
	A significant issue in low beta resonators is medium field Q-slope (MFQS) at 4K. To study the MFQS and the field dependence of surface resistance in low beta resonators, a quarter-wave resonator (QWR) and a half-wave resonator (HWR) were designed to be tested at integer harmonic frequencies of 200MHz, and up to 1.2GHz. A series of chemistry and heat treatments will be applied to these cavities so that a systemic study on the surface resistance of the coaxial resonators associating with post-processing, RF field, and frequency can be done. The detail design of these cavities and the status of cavity fabrication will be reported in this paper.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-TUPB065
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Paper

Title

Page

WEXA05

Dirty Layers, Bi-layers and Multi-layers: Insights from Muon Spin Rotation Experiments

T. Junginger, R.E. Laxdal, D.W. Storey, E. Thoeng
TRIUMF, Vancouver, Canada
D.L. Hall, M. Liepe
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
T. Junginger
HZB, Berlin, Germany
S. Posen
Fermilab, Batavia, Illinois, USA
T. Prokscha, Z. Salman, A. Suter
PSI, Villigen PSI, Switzerland
D.W. Storey
Victoria University, Victoria, B.C., Canada
T. Tan, W.K. Withanage, M.A. Wolak, X. Xi
Temple University, Philadelphia, USA
E. Thoeng
UBC & TRIUMF, Vancouver, British Columbia, Canada
A-M. Valente-Feliciano
JLab, Newport News, Virginia, USA
W.W. Wasserman
UBC, Vancouver, B.C., Canada

Funding: This research was supported by a Marie Curie International Outgoing Fellowship within the EU Seventh Framework Programme for Research and Technological Development (2007-2013).
The multilayer approach is being investigated for SRF applications since 2006 "*". More recently the option of using a bilayer system of two superconductors has been considered as an alternative approach to reach accelerating gradients beyond bulk niobium or to explain the gradient enhancement from a 120°C bake by introduction of a 'dirty layer "**"'. In this talk results are presented from two muon spin rotation experiments at TRIUMF and PSI. The former measures the field of first entry Hentry. It will be shown that MgB2 and Nb3Sn on top of Nb both push Hentry above Hc1 to a value consistent with Hsh, independent of the layer thickness. 120°C baking increases Hentry slightly but significantly above Hc1. Using the low energy muon beam at PSI we show that there is a long range proximity effect in a bilayer system of NbTiN on Nb. This effect yields a stronger decay of the RF field with depth as expected for pure NbTiN, opposite to what has been predicted for a bi-layer system due to counter current flow at the superconductor-superconductor interface "***". An insulating layer suppresses this proximity effect.
* Gurevich, A. APL 88.1 (2006)
** Checchin, M. Diss. Illinois Institute of Technology, 2016.
Kubo, T. Superconductor Science and Technology 30.2 (2016)
*** Kubo, T et al. APL 104.3 (2014)

Slides WEXA05 [3.716 MB]

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

THPB017

Investigation of Trapped Magnetic Flux in Superconducting Niobium Samples with Neutron Radiography

762

O. Kugeler, T. Junginger, J. Knobloch, M.M. Krzyzagorski, J.M. Köszegi, L. Riik, W. Treimer, R.F. Ziesche
HZB, Berlin, Germany

The dynamics of flux expulsion in Nb samples during superconducting transition has been investigated with neutron radiography. Aiming at a reduction of the trapped flux with respect to obtaining a small residual resistance it was attempted to influence the expulsion by applying external AC magnetic fields. The results of these experiments are presented.

Poster THPB017 [1.528 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-THPB017

Export •

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

MOPB042

The TRIUMF/VECC Injector Cryomodule Performance

144

Y. Ma, K. Fong, T. Junginger, D. Kishi, A.N. Koveshnikov, R.E. Laxdal, N. Muller, R.R. Nagimov, D.W. Storey, E. Thoeng, Z.Y. Yao, V. Zvyagintsev
TRIUMF, Vancouver, Canada
U. Bhunia, A. Chakrabarti, S. Dechoudhury, V. Naik
VECC, Kolkata, India

The collaboration on superconducting electron Linac for rare ion beam facilities ARIEL (Advanced Rare Iso-topE Laboratory) [1-4] and ANURIB [5] (Advanced Na-tional facility for Unstable and Rare Isotope Beams) has resulted in production of a superconducting Injector Cryomodule (VECC ICM) at TRIUMF for VECC. The cryomodule design utilizes a unique box cryomodule with a top-loading cold mass. The hermetic unit consists of a niobium cavity which operating at 1.3GHz and connected with two symmetrically opposed couplers which can deliver 100kW RF power to the beam. Liquid helium supplied at 4.4 K is converted to superfluid helium-II through a cryogenic insert on board which includes 4 K phase separator, 4K/2K heat exchanger and Joule-Thompson valve. In 2016, the VECC ICM has been tested at TRIUMF and demonstrated 10.5 MeV acceleration. A summary of the VECC ICM commissioning are presented.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-MOPB042

Export •

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

TUPB064

Operating Experience on Cavity Performance of ISAC-II Superconducting Heavy Ion Linac

527

Z.Y. Yao, T. Junginger, A.N. Koveshnikov, R.E. Laxdal, Y. Ma, D.W. Storey, E. Thoeng, B.S. Waraich, V. Zvyagintsev
TRIUMF, Vancouver, Canada

ISAC-II is a superconducting heavy ion linac with 40 QWRs as an extension of ISAC facility for ISOL based on radioactive ion beam production and acceleration. Phase-I with twenty 106MHz cavities has been operating since 2006. The design spec was achieved with the completion of Phase-II with another twenty 141MHz cavities in 2010. The cavity performance statistics and operating experience have been accumulated over years. This paper will summarize the operating experience on cavity performance of ISAC-II.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-TUPB064

Export •

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

TUPB065

Design of Multi-frequency Coaxial Test Resonators

531

Z.Y. Yao, T. Junginger, R.E. Laxdal, B. Matheson, B.S. Waraich, V. Zvyagintsev
TRIUMF, Vancouver, Canada

A significant issue in low beta resonators is medium field Q-slope (MFQS) at 4K. To study the MFQS and the field dependence of surface resistance in low beta resonators, a quarter-wave resonator (QWR) and a half-wave resonator (HWR) were designed to be tested at integer harmonic frequencies of 200MHz, and up to 1.2GHz. A series of chemistry and heat treatments will be applied to these cavities so that a systemic study on the surface resistance of the coaxial resonators associating with post-processing, RF field, and frequency can be done. The detail design of these cavities and the status of cavity fabrication will be reported in this paper.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-TUPB065

Export •

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