SRF2013 - List of Authors (Plouin, J.)

Paper

Title

Page

Experimental Investigations of the Quench Phenomena for the Quench Localization by the Second Sound Wave Method

739

J. Plouin, J.-P. Charrier, C. Magne, J. Novo
CEA/DSM/IRFU, France
L. Maurice
CEA/IRFU, Gif-sur-Yvette, France

The quench localization by the second sound method is now widely used in many laboratories. This method avoids the complicated implementation of temperature arrays around the surface cavities. Instead, specific sensors are placed around the cavity and the time of arrival of the second sound wave generated by the quench is measured on each sensor; then the distance from sensors to quench is deducted from the theoretical second sound wave velocity. In principle, the quench position can be localized with a triangulation by a limited number of sensors. However, many measurements have shown that the time of arrival of the wave was not corresponding to the theoretical second sound wave velocity: the “measured” velocity is often 50% higher than the theory. At CEA-Saclay we performed several measurements on single cell cavities to investigate these phenomena. Several hypotheses are studied: large quench spot, heat propagation by another phenomenon than the second sound near to the cavity where the heat power density is very high. These results and the discussions on these hypotheses will be presented.

WEIOD02

Magnetic Shielding: Our Experience with Various Shielding Materials

808

M. Masuzawa, A. Terashima, K. Tsuchiya
KEK, Ibaraki, Japan
A. Daël, O. Napoly, J. Plouin
CEA/DSM/IRFU, France

Magnetic shielding is a key technology for superconducting RF cavities. The tolerance of the ambient magnetic field depends on factors such as the operating RF frequency and acceleration gradient, but it can be as small as a few mG. Some high-Ni-content alloys, such as Cryperm 10 or Cryophy, which are claimed to maintain high permeability at cryogenic temperatures where superconducting cavities are operated, are commercially available at present and are used for magnetic shielding of superconducting cavities at many laboratories. Permeability measurements were made in order to understand the characteristics of such materials at both room and cryogenic temperatures, and the results will be used as a database for designing magnetic shields. It was found that the catalog performance of such materials was not always reproduced in the measurements. Some degradation was observed which depended on how the material was handled. The results of investigation into possible causes for the performance degradation of the shielding material at cryogenic temperature will be presented, along with permeability measurement results for various materials at different temperatures.

Slides WEIOD02 [8.475 MB]

FRIOC02

ESS Elliptical Cavities and Cryomodules

1218

G. Devanz, P. Bosland, M. Desmons, P. Hardy, F. Leseigneur, M. Luong, F. Peauger, J. Plouin, D. Roudier
CEA/DSM/IRFU, France
N. Bazin
CEA/IRFU, Gif-sur-Yvette, France
G. Costanza
Lund University, Lund, Sweden
G. Olivier
IPN, Orsay, France

The accelerator of the European Spallation Source (ESS) is a 5 MW proton linac to be built in Lund Sweden. Its superconducting section is composed of 3 cavity families: double spoke resonators, medium beta and high beta elliptical multicell cavities. This paper presents the electromagnetic and mechanical design of the 704.42 MHz elliptical cavities. Both elliptical famillies are housed in 4-cavity cryomodules which share a common design and set of components which will be described here.

Slides FRIOC02 [3.475 MB]

Paper	Title	Page
TUP111	Experimental Investigations of the Quench Phenomena for the Quench Localization by the Second Sound Wave Method	739
	J. Plouin, J.-P. Charrier, C. Magne, J. Novo CEA/DSM/IRFU, France L. Maurice CEA/IRFU, Gif-sur-Yvette, France
	The quench localization by the second sound method is now widely used in many laboratories. This method avoids the complicated implementation of temperature arrays around the surface cavities. Instead, specific sensors are placed around the cavity and the time of arrival of the second sound wave generated by the quench is measured on each sensor; then the distance from sensors to quench is deducted from the theoretical second sound wave velocity. In principle, the quench position can be localized with a triangulation by a limited number of sensors. However, many measurements have shown that the time of arrival of the wave was not corresponding to the theoretical second sound wave velocity: the “measured” velocity is often 50% higher than the theory. At CEA-Saclay we performed several measurements on single cell cavities to investigate these phenomena. Several hypotheses are studied: large quench spot, heat propagation by another phenomenon than the second sound near to the cavity where the heat power density is very high. These results and the discussions on these hypotheses will be presented.

WEIOD02	Magnetic Shielding: Our Experience with Various Shielding Materials	808
	M. Masuzawa, A. Terashima, K. Tsuchiya KEK, Ibaraki, Japan A. Daël, O. Napoly, J. Plouin CEA/DSM/IRFU, France
	Magnetic shielding is a key technology for superconducting RF cavities. The tolerance of the ambient magnetic field depends on factors such as the operating RF frequency and acceleration gradient, but it can be as small as a few mG. Some high-Ni-content alloys, such as Cryperm 10 or Cryophy, which are claimed to maintain high permeability at cryogenic temperatures where superconducting cavities are operated, are commercially available at present and are used for magnetic shielding of superconducting cavities at many laboratories. Permeability measurements were made in order to understand the characteristics of such materials at both room and cryogenic temperatures, and the results will be used as a database for designing magnetic shields. It was found that the catalog performance of such materials was not always reproduced in the measurements. Some degradation was observed which depended on how the material was handled. The results of investigation into possible causes for the performance degradation of the shielding material at cryogenic temperature will be presented, along with permeability measurement results for various materials at different temperatures.
	Slides WEIOD02 [8.475 MB]

FRIOC02	ESS Elliptical Cavities and Cryomodules	1218
	G. Devanz, P. Bosland, M. Desmons, P. Hardy, F. Leseigneur, M. Luong, F. Peauger, J. Plouin, D. Roudier CEA/DSM/IRFU, France N. Bazin CEA/IRFU, Gif-sur-Yvette, France G. Costanza Lund University, Lund, Sweden G. Olivier IPN, Orsay, France
	The accelerator of the European Spallation Source (ESS) is a 5 MW proton linac to be built in Lund Sweden. Its superconducting section is composed of 3 cavity families: double spoke resonators, medium beta and high beta elliptical multicell cavities. This paper presents the electromagnetic and mechanical design of the 704.42 MHz elliptical cavities. Both elliptical famillies are housed in 4-cavity cryomodules which share a common design and set of components which will be described here.
	Slides FRIOC02 [3.475 MB]