SRF2019 - Classification: Cavities - Fabrication / cavity test diagnostics

Paper	Title	Page
THP067	Cavity Tilt Measurement in a 1.3 GHz Superconducting Cryo-Module at FLASH	1041
	J.H. Wei USTC/NSRL, Hefei, Anhui, People’s Republic of China N. Baboi DESY, Hamburg, Germany T. Hellert LBNL, Berkeley, California, USA
	TESLA superconducting (SC) cavities are used for the acceleration of electron bunches at FLASH. The Higher Order Modes (HOMs) excited by the beam in these cavities may cause emittance growth. The misalignment of the cavities in a cryo-module is one of the essential factors which enhance the coupling of the HOMs to the beam. The cavity offset and tilt are the two most relevant misalignments. These can be measured by help of dipole modes, based on their linear dependence on the beam offset. The cavity offset has been measured before in several modules at FLASH. However, the cavity tilt has so far proved to be difficult to be measured, because the angular dependence of the dipole mode is much weaker. By carefully targeting the beam through the middle of a cavity, the strong offset contribution to the dipole fields could be reduced. Careful data analysis based on a fitting method enabled us then to extract the information on the cavity tilt. This measurement has been implemented in the cavities in one cryo-module at FLASH. First results of the ongoing measurements from several cavities are presented in this paper. It is for the first time that the cavity tilt in several cavities has been measured.
	Poster THP067 [1.392 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-THP067
About •	paper received ※ 23 June 2019 paper accepted ※ 29 June 2019 issue date ※ 14 August 2019
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THP086	Preliminary Design of Superconducting Cavity Test Platform in CSNS Campus	1104
	S.H. Liu, X. Li, W. Long, H. Sun, S. Wang, C.L. Zhang, J.Y. Zhu IHEP, People’s Republic of China S.Y. Chen, Y. Liu, C. Shi DNSC, Dongguan, People’s Republic of China P.C. Wang, B. Wu IHEP CSNS, Guangdong Province, People’s Republic of China
	For the beam power upgrade of CSNS (China Spallation Neutron Source) and the construction of the high performance photon source in South China in the near future, the superconducting cavity test platform which includes vertical test stand, single cavity horizontal test stand, cryomodule horizontal test stand and coupler test stand will be built. This paper will generally introduce the preliminary design of the test platform and corresponding test parameters.
	Poster THP086 [0.171 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-THP086
About •	paper received ※ 21 June 2019 paper accepted ※ 01 July 2019 issue date ※ 14 August 2019
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THP087	2 K SUPERFLUID HELIUM CRYOGENIC VERTICAL TEST STAND OF PAPS	1107
	L.R. Sun, R. Ge, R. Han, Y.C. Jiang, S.P. Li, C.C. Ma, M.J. Sang, M.F. Xu, R. Ye, J.H. Zhang, X.Z. Zhang, Z.Z. Zhang, T.X. Zhao IHEP, Beijing, People’s Republic of China
	Platform of Advanced Photon Source Technology R&D (PAPS) in the Institute of High Energy Physics (IHEP) is an ongoing project, which aimed to provide a comprehensive research and testing platform for the particle accelerator, X-ray detection and optics. As one of the important parts of the platform, cryogenic vertical test stand for the superconducting cavities is composed of three big vertical test cryostats with 2 different inner diameters, which can provide 4.5K liquid helium, 2K superfluid helium and the lowest 1.5K environments according to the cavities test requirements. The cryogen-ic vertical test stands also focus on current international ¿hot spot¿ fast cool down to the superconducting cavi-ties, maximum liquid helium mass flow rate can be reached to 80g/s. Because of the big size of the cryostats and certain scale, the finished cryogenic vertical test stand can meet several different type cavities test, such as 1.3GHz 9cell, Spoke, elliptical, etc. And also can provide the cavities¿ mass vertical testing for the large scale superconducting accelerators.
	Poster THP087 [1.182 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-THP087
About •	paper received ※ 20 June 2019 paper accepted ※ 01 July 2019 issue date ※ 14 August 2019
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THP088	Updates on the Inspection System for SRF Cavities	1111
	Y. Iwashita, H. Tongu Kyoto ICR, Uji, Kyoto, Japan H. Hayano KEK, Ibaraki, Japan Y. Kuriyama Kyoto University, Research Reactor Institute, Osaka, Japan
	Optical inspections on superconducting cavities are familiar to those who are involved in the cavity fabrications. Further improvements on the Kyoto Camera have been carried out these years together with further processing technique developments, such as removing found defects by local grinding techniques. Improvements on Kyoto Camera includes implementation of color LEDs for illumination system, which improves the inspection efficiency. These progresses will be reported.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-THP088
About •	paper received ※ 02 July 2019 paper accepted ※ 03 July 2019 issue date ※ 14 August 2019
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THP089	Development of Superconducting RF Double Spoke Cavity at IHEP	1114
SUSP010	use link to see paper's listing under its alternate paper code
	Q. Zhou, F.S. He, W.M. Pan IHEP, Beijing, People’s Republic of China
	The China Spallation Neutron Source (CSNS) is de-signed to produce spallation neutrons. CSNS upgrade is planned to increase beam power by inserting a SRF linac after drift tube linac (DTL). IHEP is developing a 325MHz double spoke cavity at ¿0 of 0.5 for the CSNS SRF linac. The cavity shape was optimized to minimize Ep/Ea while keeping Bp/Ep reasonably low. Meanwhile, mechanical design was applied to check stress, Lorentz force detuning and microphonic effects, and to minimize pressure sensitivity. A new RF coupling scheme was pro-posed to avoid electrons hitting directly on ceramic win-dow. After fabrication and post processing of cavity, the cavity reached Bp of 120mT at E_acc = 13.8MV/m and Q₀ = 1.72·10¹⁰ under vertical test at 2K.
	Poster THP089 [2.176 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-THP089
About •	paper received ※ 22 June 2019 paper accepted ※ 30 June 2019 issue date ※ 14 August 2019
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THP090	Characterization of SSR1 Cavities for PIP-II Linac	1120
	A.I. Sukhanov, F.G. Garcia, B.M. Hanna, S. Kazakov, Y.M. Pischalnikov, O.V. Prokofiev, W. Schappert, I. Terechkine, V.P. Yakovlev, J.C. Yun Fermilab, Batavia, Illinois, USA C. Contreras-Martinez FRIB, East Lansing, Michigan, USA S. Samani Queen Mary University of London, London, United Kingdom
	A cryomodule of 325 MHz Single Spoke Resonator type 1 (SSR1) superconducting RF cavities is being built at Fermilab for the PIP-II project. Twelve SSR1 cavities were manufactured in industry in USA (10 cavities) and India (2 cavities) and delivered to Fermilab. In this paper we present results of characterization of fully integrated jacketed cavities with high power coupler and tuner at the Fermilab Spoke Test Cryostat (STC).
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-THP090
About •	paper received ※ 23 June 2019 paper accepted ※ 01 July 2019 issue date ※ 14 August 2019
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THP093	Upgrade on the Experimental Activities for ESS at the LASA Vertical Test Facility	1133
	M. Bertucci, A. Bosotti, A. D’Ambros, P. Michelato, L. Monaco, C. Pagani, R. Paparella, D. Sertore INFN/LASA, Segrate (MI), Italy
	The LASA vertical test facility is equipped for the cold test of ESS medium-beta 704.42 MHz cavities, with and without He tank, and is integrated with several diagnostic tools allowing a careful analysis of cavity performance limitations. This paper reports the latest tests on ESS cavities - both prototypes and series - and a discussion on the experimental results. The recent instrumental upgrades implemented in the facility - and the ones foreseen for the future in view of a further improvement of cavity performances - are also pointed out.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-THP093
About •	paper received ※ 24 June 2019 paper accepted ※ 30 June 2019 issue date ※ 14 August 2019
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THP095	Direct Measurement of Thermoelectric Currents During Cool Down	1139
	A.E. Ivanov, F. Gerigk, A. Macpherson CERN, Geneva, Switzerland
	In recent years there has been much discussion on thermoelectric effects and their role in flux expulsion during cool down of SRF cavities. Magnetic field is often measured to asses both flux expulsion as the cavity undergoes superconducting transition, and thermoelectric currents due to spatial thermal gradients. As a complementary view, in this paper we show direct measurement of the thermoelectric current independent from the expulsion measurement of the magnetic field. In our setup the azimuthally symmetric cavity is vertically installed and the thermal gradient is along the symmetry axis allowing to describe the cool down behavior of the thermoelectric current using simple coupled simulations.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-THP095
About •	paper received ※ 21 June 2019 paper accepted ※ 30 June 2019 issue date ※ 14 August 2019
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THP096	ESS Prototype Cavities Developed at CEA Saclay	1143
	E. Cenni CEA-IRFU, Gif-sur-Yvette, France M. Baudrier, P. Carbonnier, G. Devanz, X. Hanus, L. Maurice, J. Plouin, D. Roudier, P. Sahuquet CEA-DRF-IRFU, France
	The ESS elliptical superconducting Linac consists of two types of 704.42 MHz cavities, medium and high beta, to accelerate the beam from 216 MeV up to the final energy at 2 GeV. The medium and high-beta parts of the Linac are composed of 36 and 84 elliptical cavities, with geometrical beta values of 0.67 and 0.86 respectively. CEA Saclay is in charge of the cavity prototypes that is designing, manufacturing, testing and integrating them into demonstrator cryomodules. We have manufactured 6 medium beta and 5 high beta cavities and we present here the latest results concerning these activities.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-THP096
About •	paper received ※ 22 June 2019 paper accepted ※ 02 July 2019 issue date ※ 14 August 2019
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THP097	Field Emission Studies on ESS Elliptical Prototype Cavities at CEA Saclay	1147
	E. Cenni, M. Baudrier, G. Devanz, L. Maurice, O. Piquet, D. Roudier CEA-DRF-IRFU, France
	CEA Saclay is in charge of the cavity prototypes that is designing, manufacturing, testing and integrating them into demonstrator cryomodules. We have manufactured 6 medium beta and 5 high beta cavities. As part of these activities we are interested in field emission as one of the limiting factors for cavity performances. We are currently collecting data from cavities operated in vertical cryostat and inside cryomodules. Analysis are carried out by means of particle tracking simulation and comparison with radiation dose monitor and scintillators.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-THP097
About •	paper received ※ 27 June 2019 paper accepted ※ 01 July 2019 issue date ※ 14 August 2019
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THP105	Thermal Mapping of SRF Cavities by Second Sound Detection With Transition Edge Sensors and Oscillating Superleak Transducers	1182
	G. Vandoni, T. Koettig, A. Macpherson, K. Turaj, L. Vega Cid CERN, Meyrin, Switzerland H. Furci EPFL, Lausanne, Switzerland
	The SRF cavity testing facilities at CERN include four vertical cryostat stations in SM18 and a cryostat for small cavities in the Cryolab. A large range of structures are tested, from Nb thin film cavities for HIE-Isolde and LHC, to bulk Nb crab cavities for HiLumi or 704 MHz 5-cell high-gradient cavities. To cope with different shapes and small series tests, thermal mapping diagnostics is deployed by sensing second sound in superfluid helium. A new type of Transition Edge Sensors (TES) has been developed in the last 2 years. These are miniature resistors of thin-film superconducting alloys, micro-produced on insulating wafers. An extensive campaign of optimization of design, fabrication process and composition was accompanied by qualification in a calibration cryostat. Reproducibility, stability, then intensity, distance and angular dependence of the response were assessed and compared to Oscillating Superleak Transducers (OST). The TES were then installed in a vertical cryostat for tests of a prototype crab cavity for HiLumi. TES are now applied to quench localization on high gradient cavities, for which the most recent results will be presented, together with the OST results.
	Poster THP105 [2.186 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-THP105
About •	paper received ※ 23 June 2019 paper accepted ※ 30 June 2019 issue date ※ 14 August 2019
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FRCAB8	Systematic Studies of the Second Sound Method for Quench Detection of Superconducting Radio Frequency Cavities	1239
	L. Steder, B. Bein, D. Reschke DESY, Hamburg, Germany W. Hillert University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany
	DESY conducts R&D for SRF cavities, part of the manifold activities are vertical performance tests. Besides the determination of accelerating gradient and quality factor, additional sensors and diagnostic methods are used to obtain more information about the cavity behaviour and the test environment. The second sound system is a tool for spatially resolved quench detection via oscillating super-leak transducers, they record the second sound wave, generated by the quench of the superconducting Niobium. The mounting of the sensors was improved to reduce systematic uncertainties and results of a recent master thesis are presented in the following. Different reconstruction methods are used to determine the origin of the waves. The precision, constraints and limits of these are compared. To introduce an external reference and to qualify the different methods a calibration tool was used. It injects short heat pulses to resistors at exact known space and time coordinates. Results obtained by the different algorithms and measurements with the calibration tool are presented with an emphasis on the possible spatial resolution and the estimation of systematic uncertainties of the methods.
	Slides FRCAB8 [3.039 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-FRCAB8
About •	paper received ※ 21 June 2019 paper accepted ※ 30 June 2019 issue date ※ 14 August 2019
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

Paper

Title

Page

Cavity Tilt Measurement in a 1.3 GHz Superconducting Cryo-Module at FLASH

1041

J.H. Wei
USTC/NSRL, Hefei, Anhui, People’s Republic of China
N. Baboi
DESY, Hamburg, Germany
T. Hellert
LBNL, Berkeley, California, USA

TESLA superconducting (SC) cavities are used for the acceleration of electron bunches at FLASH. The Higher Order Modes (HOMs) excited by the beam in these cavities may cause emittance growth. The misalignment of the cavities in a cryo-module is one of the essential factors which enhance the coupling of the HOMs to the beam. The cavity offset and tilt are the two most relevant misalignments. These can be measured by help of dipole modes, based on their linear dependence on the beam offset. The cavity offset has been measured before in several modules at FLASH. However, the cavity tilt has so far proved to be difficult to be measured, because the angular dependence of the dipole mode is much weaker. By carefully targeting the beam through the middle of a cavity, the strong offset contribution to the dipole fields could be reduced. Careful data analysis based on a fitting method enabled us then to extract the information on the cavity tilt. This measurement has been implemented in the cavities in one cryo-module at FLASH. First results of the ongoing measurements from several cavities are presented in this paper. It is for the first time that the cavity tilt in several cavities has been measured.

Poster THP067 [1.392 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-THP067

About •

paper received ※ 23 June 2019 paper accepted ※ 29 June 2019 issue date ※ 14 August 2019

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

THP086

Preliminary Design of Superconducting Cavity Test Platform in CSNS Campus

1104

S.H. Liu, X. Li, W. Long, H. Sun, S. Wang, C.L. Zhang, J.Y. Zhu
IHEP, People’s Republic of China
S.Y. Chen, Y. Liu, C. Shi
DNSC, Dongguan, People’s Republic of China
P.C. Wang, B. Wu
IHEP CSNS, Guangdong Province, People’s Republic of China

For the beam power upgrade of CSNS (China Spallation Neutron Source) and the construction of the high performance photon source in South China in the near future, the superconducting cavity test platform which includes vertical test stand, single cavity horizontal test stand, cryomodule horizontal test stand and coupler test stand will be built. This paper will generally introduce the preliminary design of the test platform and corresponding test parameters.

Poster THP086 [0.171 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-THP086

About •

paper received ※ 21 June 2019 paper accepted ※ 01 July 2019 issue date ※ 14 August 2019

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

THP087

2 K SUPERFLUID HELIUM CRYOGENIC VERTICAL TEST STAND OF PAPS

1107

L.R. Sun, R. Ge, R. Han, Y.C. Jiang, S.P. Li, C.C. Ma, M.J. Sang, M.F. Xu, R. Ye, J.H. Zhang, X.Z. Zhang, Z.Z. Zhang, T.X. Zhao
IHEP, Beijing, People’s Republic of China

Platform of Advanced Photon Source Technology R&D (PAPS) in the Institute of High Energy Physics (IHEP) is an ongoing project, which aimed to provide a comprehensive research and testing platform for the particle accelerator, X-ray detection and optics. As one of the important parts of the platform, cryogenic vertical test stand for the superconducting cavities is composed of three big vertical test cryostats with 2 different inner diameters, which can provide 4.5K liquid helium, 2K superfluid helium and the lowest 1.5K environments according to the cavities test requirements. The cryogen-ic vertical test stands also focus on current international ¿hot spot¿ fast cool down to the superconducting cavi-ties, maximum liquid helium mass flow rate can be reached to 80g/s. Because of the big size of the cryostats and certain scale, the finished cryogenic vertical test stand can meet several different type cavities test, such as 1.3GHz 9cell, Spoke, elliptical, etc. And also can provide the cavities¿ mass vertical testing for the large scale superconducting accelerators.

Poster THP087 [1.182 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-THP087

About •

paper received ※ 20 June 2019 paper accepted ※ 01 July 2019 issue date ※ 14 August 2019

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THP088

Updates on the Inspection System for SRF Cavities

1111

Y. Iwashita, H. Tongu
Kyoto ICR, Uji, Kyoto, Japan
H. Hayano
KEK, Ibaraki, Japan
Y. Kuriyama
Kyoto University, Research Reactor Institute, Osaka, Japan

Optical inspections on superconducting cavities are familiar to those who are involved in the cavity fabrications. Further improvements on the Kyoto Camera have been carried out these years together with further processing technique developments, such as removing found defects by local grinding techniques. Improvements on Kyoto Camera includes implementation of color LEDs for illumination system, which improves the inspection efficiency. These progresses will be reported.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-THP088

About •

paper received ※ 02 July 2019 paper accepted ※ 03 July 2019 issue date ※ 14 August 2019

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

THP089

Development of Superconducting RF Double Spoke Cavity at IHEP

1114

SUSP010

use link to see paper's listing under its alternate paper code

Q. Zhou, F.S. He, W.M. Pan
IHEP, Beijing, People’s Republic of China

The China Spallation Neutron Source (CSNS) is de-signed to produce spallation neutrons. CSNS upgrade is planned to increase beam power by inserting a SRF linac after drift tube linac (DTL). IHEP is developing a 325MHz double spoke cavity at ¿0 of 0.5 for the CSNS SRF linac. The cavity shape was optimized to minimize Ep/Ea while keeping Bp/Ep reasonably low. Meanwhile, mechanical design was applied to check stress, Lorentz force detuning and microphonic effects, and to minimize pressure sensitivity. A new RF coupling scheme was pro-posed to avoid electrons hitting directly on ceramic win-dow. After fabrication and post processing of cavity, the cavity reached Bp of 120mT at E_acc = 13.8MV/m and Q₀ = 1.72·10¹⁰ under vertical test at 2K.

Poster THP089 [2.176 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-THP089

About •

paper received ※ 22 June 2019 paper accepted ※ 30 June 2019 issue date ※ 14 August 2019

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THP090

Characterization of SSR1 Cavities for PIP-II Linac

1120

A.I. Sukhanov, F.G. Garcia, B.M. Hanna, S. Kazakov, Y.M. Pischalnikov, O.V. Prokofiev, W. Schappert, I. Terechkine, V.P. Yakovlev, J.C. Yun
Fermilab, Batavia, Illinois, USA
C. Contreras-Martinez
FRIB, East Lansing, Michigan, USA
S. Samani
Queen Mary University of London, London, United Kingdom

A cryomodule of 325 MHz Single Spoke Resonator type 1 (SSR1) superconducting RF cavities is being built at Fermilab for the PIP-II project. Twelve SSR1 cavities were manufactured in industry in USA (10 cavities) and India (2 cavities) and delivered to Fermilab. In this paper we present results of characterization of fully integrated jacketed cavities with high power coupler and tuner at the Fermilab Spoke Test Cryostat (STC).

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-THP090

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paper received ※ 23 June 2019 paper accepted ※ 01 July 2019 issue date ※ 14 August 2019

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

THP093

Upgrade on the Experimental Activities for ESS at the LASA Vertical Test Facility

1133

M. Bertucci, A. Bosotti, A. D’Ambros, P. Michelato, L. Monaco, C. Pagani, R. Paparella, D. Sertore
INFN/LASA, Segrate (MI), Italy

The LASA vertical test facility is equipped for the cold test of ESS medium-beta 704.42 MHz cavities, with and without He tank, and is integrated with several diagnostic tools allowing a careful analysis of cavity performance limitations. This paper reports the latest tests on ESS cavities - both prototypes and series - and a discussion on the experimental results. The recent instrumental upgrades implemented in the facility - and the ones foreseen for the future in view of a further improvement of cavity performances - are also pointed out.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-THP093

About •

paper received ※ 24 June 2019 paper accepted ※ 30 June 2019 issue date ※ 14 August 2019

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THP095

Direct Measurement of Thermoelectric Currents During Cool Down

1139

A.E. Ivanov, F. Gerigk, A. Macpherson
CERN, Geneva, Switzerland

In recent years there has been much discussion on thermoelectric effects and their role in flux expulsion during cool down of SRF cavities. Magnetic field is often measured to asses both flux expulsion as the cavity undergoes superconducting transition, and thermoelectric currents due to spatial thermal gradients. As a complementary view, in this paper we show direct measurement of the thermoelectric current independent from the expulsion measurement of the magnetic field. In our setup the azimuthally symmetric cavity is vertically installed and the thermal gradient is along the symmetry axis allowing to describe the cool down behavior of the thermoelectric current using simple coupled simulations.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-THP095

About •

paper received ※ 21 June 2019 paper accepted ※ 30 June 2019 issue date ※ 14 August 2019

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THP096

ESS Prototype Cavities Developed at CEA Saclay

1143

E. Cenni
CEA-IRFU, Gif-sur-Yvette, France
M. Baudrier, P. Carbonnier, G. Devanz, X. Hanus, L. Maurice, J. Plouin, D. Roudier, P. Sahuquet
CEA-DRF-IRFU, France

The ESS elliptical superconducting Linac consists of two types of 704.42 MHz cavities, medium and high beta, to accelerate the beam from 216 MeV up to the final energy at 2 GeV. The medium and high-beta parts of the Linac are composed of 36 and 84 elliptical cavities, with geometrical beta values of 0.67 and 0.86 respectively. CEA Saclay is in charge of the cavity prototypes that is designing, manufacturing, testing and integrating them into demonstrator cryomodules. We have manufactured 6 medium beta and 5 high beta cavities and we present here the latest results concerning these activities.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-THP096

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paper received ※ 22 June 2019 paper accepted ※ 02 July 2019 issue date ※ 14 August 2019

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THP097

Field Emission Studies on ESS Elliptical Prototype Cavities at CEA Saclay

1147

E. Cenni, M. Baudrier, G. Devanz, L. Maurice, O. Piquet, D. Roudier
CEA-DRF-IRFU, France

CEA Saclay is in charge of the cavity prototypes that is designing, manufacturing, testing and integrating them into demonstrator cryomodules. We have manufactured 6 medium beta and 5 high beta cavities. As part of these activities we are interested in field emission as one of the limiting factors for cavity performances. We are currently collecting data from cavities operated in vertical cryostat and inside cryomodules. Analysis are carried out by means of particle tracking simulation and comparison with radiation dose monitor and scintillators.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-THP097

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paper received ※ 27 June 2019 paper accepted ※ 01 July 2019 issue date ※ 14 August 2019

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THP105

Thermal Mapping of SRF Cavities by Second Sound Detection With Transition Edge Sensors and Oscillating Superleak Transducers

1182

G. Vandoni, T. Koettig, A. Macpherson, K. Turaj, L. Vega Cid
CERN, Meyrin, Switzerland
H. Furci
EPFL, Lausanne, Switzerland

The SRF cavity testing facilities at CERN include four vertical cryostat stations in SM18 and a cryostat for small cavities in the Cryolab. A large range of structures are tested, from Nb thin film cavities for HIE-Isolde and LHC, to bulk Nb crab cavities for HiLumi or 704 MHz 5-cell high-gradient cavities. To cope with different shapes and small series tests, thermal mapping diagnostics is deployed by sensing second sound in superfluid helium. A new type of Transition Edge Sensors (TES) has been developed in the last 2 years. These are miniature resistors of thin-film superconducting alloys, micro-produced on insulating wafers. An extensive campaign of optimization of design, fabrication process and composition was accompanied by qualification in a calibration cryostat. Reproducibility, stability, then intensity, distance and angular dependence of the response were assessed and compared to Oscillating Superleak Transducers (OST). The TES were then installed in a vertical cryostat for tests of a prototype crab cavity for HiLumi. TES are now applied to quench localization on high gradient cavities, for which the most recent results will be presented, together with the OST results.

Poster THP105 [2.186 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-THP105

About •

paper received ※ 23 June 2019 paper accepted ※ 30 June 2019 issue date ※ 14 August 2019

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FRCAB8

Systematic Studies of the Second Sound Method for Quench Detection of Superconducting Radio Frequency Cavities

1239

L. Steder, B. Bein, D. Reschke
DESY, Hamburg, Germany
W. Hillert
University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany

DESY conducts R&D for SRF cavities, part of the manifold activities are vertical performance tests. Besides the determination of accelerating gradient and quality factor, additional sensors and diagnostic methods are used to obtain more information about the cavity behaviour and the test environment. The second sound system is a tool for spatially resolved quench detection via oscillating super-leak transducers, they record the second sound wave, generated by the quench of the superconducting Niobium. The mounting of the sensors was improved to reduce systematic uncertainties and results of a recent master thesis are presented in the following. Different reconstruction methods are used to determine the origin of the waves. The precision, constraints and limits of these are compared. To introduce an external reference and to qualify the different methods a calibration tool was used. It injects short heat pulses to resistors at exact known space and time coordinates. Results obtained by the different algorithms and measurements with the calibration tool are presented with an emphasis on the possible spatial resolution and the estimation of systematic uncertainties of the methods.

Slides FRCAB8 [3.039 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-FRCAB8

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paper received ※ 21 June 2019 paper accepted ※ 30 June 2019 issue date ※ 14 August 2019

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