SRF2017 - List of Keywords (detector)

Paper	Title	Other Keywords	Page
TUPB085	Quench Detection on Superconducting Cavity by Second Sound	ion, cavity, site, SRF	589
	Z.C. Liu, J. Gao, F.S. He, H.Y. Lin, P. Zhang IHEP, Beijing, People's Republic of China
	High gradient is very important for superconducting cavity, however it may be limited by quench on the cavity high field region. Quench can be caused by various reasons. To locate the position is the key to reveal the mysteries of quench. OST sensor was widely used to locate the quench position. Now we are developing the quench position detection system by RTD sensors such as Cernox. In this paper, we will show the design of the second sound system and testing results on the QWR cavity.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-TUPB085
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THXA06	Advanced OST System for the Second-sound Test of Fully Dressed Cavities	ion, cavity, power-supply, FEL	703
	Y. Tamashevich HZB, Berlin, Germany Y. Tamashevich University of Hamburg, Hamburg, Germany
	Cavities which exhibit a low field quench are normally discarded from usage in accelerator projects. However, they can be repaired if the exact location of the quench is known. Optical inspection alone cannot reliably locate the source of a quench. Methods that directly measure the quench, such as thermometry or second sound detection, could so far only be performed at undressed cavities. A new, specially designed, second-sound system for the first time allows the localization of the quench in multicell cavities equipped with a helium vessel. It can be easily installed in the helium pipe of the cavity. Information on the quench location can be acquired during a standard rf test. A new algorithm localizes the quench based on the real path of the second-sound wave around the cavity surface, rather than using simple triangulation. The implemented pathfinding method leads to a high precision and high accuracy of the quench location. This was verified by testing standard dressed 9-cell XFEL cavities. The system can be easily applied to other cavity shapes and sizes.
	Slides THXA06 [9.681 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-THXA06
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THPB017	Investigation of Trapped Magnetic Flux in Superconducting Niobium Samples with Neutron Radiography	ion, neutron, niobium, experiment	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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THPB041	Cavity Quench Studies in Nb3Sn Using Temperature Mapping and Surface Analysis of Cavity Cut-outs	ion, cavity, niobium, electron	840
	D.L. Hall, M. Liepe, R.D. Porter Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA P. Cueva, D. Liarte, D.A. Muller, J.P. Sethna Cornell University, Ithaca, New York, USA
	Previous experimental studies on single-cell Nb3Sn cavities have shown that the cause of quench is isolated to a localised defect on the cavity surface. Here, cavity temperature mapping has been used to investigate cavity quench behaviour in an Nb3Sn cavity by measuring the temperature at the quench location as the RF field approaches the quench field. The heating profile observed at the quench location prior to quench appears to suggest quantised vortex entry at a defect. To investigate further, the quench region has been removed from the cavity and analysed using SEM methods. These results are compared to theoretical models describing two vortex entry defect candidates: regions of thin-layer tin-depleted Nb3Sn on the cavity surface that lower the flux entry field, and grain boundaries acting as Josephson junctions with a lower critical current than the surrounding material. A theoretical model of layer growth developed using density functional theory is used to discuss alterations to the coating process that could mitigate the formation of such defects.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-THPB041
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

Paper

Title

Other Keywords

Page

TUPB085

Quench Detection on Superconducting Cavity by Second Sound

ion, cavity, site, SRF

589

Z.C. Liu, J. Gao, F.S. He, H.Y. Lin, P. Zhang
IHEP, Beijing, People's Republic of China

High gradient is very important for superconducting cavity, however it may be limited by quench on the cavity high field region. Quench can be caused by various reasons. To locate the position is the key to reveal the mysteries of quench. OST sensor was widely used to locate the quench position. Now we are developing the quench position detection system by RTD sensors such as Cernox. In this paper, we will show the design of the second sound system and testing results on the QWR cavity.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-TUPB085

Export •

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

THXA06

Advanced OST System for the Second-sound Test of Fully Dressed Cavities

ion, cavity, power-supply, FEL

703

Y. Tamashevich
HZB, Berlin, Germany
Y. Tamashevich
University of Hamburg, Hamburg, Germany

Cavities which exhibit a low field quench are normally discarded from usage in accelerator projects. However, they can be repaired if the exact location of the quench is known. Optical inspection alone cannot reliably locate the source of a quench. Methods that directly measure the quench, such as thermometry or second sound detection, could so far only be performed at undressed cavities. A new, specially designed, second-sound system for the first time allows the localization of the quench in multicell cavities equipped with a helium vessel. It can be easily installed in the helium pipe of the cavity. Information on the quench location can be acquired during a standard rf test. A new algorithm localizes the quench based on the real path of the second-sound wave around the cavity surface, rather than using simple triangulation. The implemented pathfinding method leads to a high precision and high accuracy of the quench location. This was verified by testing standard dressed 9-cell XFEL cavities. The system can be easily applied to other cavity shapes and sizes.

Slides THXA06 [9.681 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-THXA06

Export •

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

ion, neutron, niobium, experiment

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)

THPB041

Cavity Quench Studies in Nb3Sn Using Temperature Mapping and Surface Analysis of Cavity Cut-outs

ion, cavity, niobium, electron

840

D.L. Hall, M. Liepe, R.D. Porter
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
P. Cueva, D. Liarte, D.A. Muller, J.P. Sethna
Cornell University, Ithaca, New York, USA

Previous experimental studies on single-cell Nb3Sn cavities have shown that the cause of quench is isolated to a localised defect on the cavity surface. Here, cavity temperature mapping has been used to investigate cavity quench behaviour in an Nb3Sn cavity by measuring the temperature at the quench location as the RF field approaches the quench field. The heating profile observed at the quench location prior to quench appears to suggest quantised vortex entry at a defect. To investigate further, the quench region has been removed from the cavity and analysed using SEM methods. These results are compared to theoretical models describing two vortex entry defect candidates: regions of thin-layer tin-depleted Nb3Sn on the cavity surface that lower the flux entry field, and grain boundaries acting as Josephson junctions with a lower critical current than the surrounding material. A theoretical model of layer growth developed using density functional theory is used to discuss alterations to the coating process that could mitigate the formation of such defects.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-THPB041

Export •

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