SRF2017 - List of Keywords (cryogenics)

Paper	Title	Other Keywords	Page
MOPB035	Cryogenic Probe Station at Old Dominion University Center for Accelerator Science	ion, cavity, SRF, niobium	128
	J. Makita, J.R. Delayen, A.V. Gurevich ODU, Norfolk, Virginia, USA G. Ciovati JLab, Newport News, Virginia, USA
	With a growing effort in research and development of an alternative material to bulk Nb for a superconducting radiofrequency (SRF) cavity, it is important to have a cost effective method to benchmark new materials of choice. At Old Dominion University's Center for Accelerator Science, a cryogenic probe station (CPS) will be used to measure the response of superconductor samples under RF fields. The setup consists of a closed-cycle refrigerator for cooling a sample wafer to a cryogenic temperature, a superconducting magnet providing a field parallel to the sample, and DC probes in addition to RF probes. The RF probes will extract a quality factor from a sample patterned in a coplanar waveguide resonator structure on a 2' wafer. From the measured quality factor, the surface resistance and the penetration depth as a function of temperature and magnetic field will be calculated. This paper will discuss the design and measurement procedures of the current CPS setup.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-MOPB035
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MOPB037	Progress of the 2x4-Cell Superconducting Accelerator for the CAEP THz-FEL Facility	ion, cavity, pick-up, cryomodule	134
	K. Zhou, C.L. Lao, M. Li, X. Luo, L.J. Shan, X. Shen, H. Wang, X. Yang CAEP/IAE, Mianyang, Sichuan, People's Republic of China X.Y. Lu PKU, Beijing, People's Republic of China
	The high average power THz radiation facility is now under construction in China Academy of Engineering Physics. The superconducting accelerator is one of the most important components for this facility, including two 4-Cell TESLA superconducting radio frequency cavities. The designed effective field gradients for both cavities are 10^-12 MV/m. This paper will present the progress of the 2x4-cell superconducting accelerator, mainly including its construction and cryogenic test in Chengdu. At 2 K state, the cryomodule works smoothly and stably. The effective field gradients of both cavities have achieved 10 MV/m. Further beam loading experiments are now in progress.
	Poster MOPB037 [5.124 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-MOPB037
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MOPB045	JLab New Injector Cryomodule Design, Fabrication and Testing	cavity, ion, cryomodule, HOM	158
	G. Cheng, M.A. Drury, J.F. Fischer, R. Kazimi, K. Macha, H. Wang JLab, Newport News, Virginia, USA
	Funding: U.S. DOE Contract No. DE-AC05-06OR23177. A new Injector Cryomodule (INJ CM) aimed to replace the existing Quarter Cryomodule in the CEBAF tunnel has been developed at Jefferson Lab (JLab). It is sched-uled to be first tested in the Cryomodule Test Facility (CMTF) for module performance then the Upgraded Injector Test Facility (UITF) with electron beam. This new cryomodule, hosting a 2-cell and 7-cell cavity, is designed to boost the electron energy from 200 keV to 5 MeV and permit 380 uA - 1.0 mA of beam current. The 2-cell cavity is a new design whereas the 7-cell cavity is refurbished from a low loss cavity from the retired JLab Renascence Cryomodule. The INJ CM adopts quite a few designs from the JLab 12 GeV Upgrade Cryomodule (C100). Examples of this include having the cold mass hung from a spaceframe structure by use of axial and transverse Nitronic rods, cavities to be tuned by scissor-jack style tuners and the end cans are actually modified from C100 style end cans. However, this new INJ CM is not a quarter of the C100 Cryomodule. This paper focuses on the major design features, fabrication and alignment process and testing of the module and its components. Authored by Jefferson Science Associates, LLC. The U.S. Government retains a non-exclusive, paid-up, irrevocable, world-wide license to publish or reproduce this manuscript for Government purposes.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-MOPB045
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MOPB069	Design of the High Power Input Coupler for CEPC Main Ring Cavity *	ion, cavity, coupling, vacuum	216
	T.M. Huang, Q. Ma, J.Y. Zhai IHEP, Beijing, People's Republic of China K.X. Gu Institute of High Energy Physics (IHEP), Chinese Academy of Sciences, Beijing, People's Republic of China
	The main ring cavities of CEPC project are two-cell el-liptical superconducting cavities operating at 650 MHz in CW mode. Each cavity equips with one high power input coupler and each coupler has to deliver at least 300 kW of CW RF power to the beam. A variable coupling from 10⁵ to 2·10⁶ is required to meet different operation modes. Considering the cavities working with high quali-ty factor up to 2·10¹⁰, the coupler assembled with cavity in class 10 clean room is strongly recommended to protect the cavity from contamination. Also, low cryogenic heat loss is one of the important issues for a large scale CW operation machine. Some of the above requirements should be compromise. Therefore, it's a big challenge to design a high power input coupler fulfilling the above requirements simultaneously. A new coupler that employs 75 Ω coaxial line sections, a planar ceramic disk win-dow, a coaxial to waveguide transition and a coupling adjusting actuator has been designed. In this paper, the RF design, thermal stress analysis and preliminary me-chanical design of the coupler are presented.
	Poster MOPB069 [0.735 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-MOPB069
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MOPB087	Frequency Tuner Development and Testing at Cornell for the RAON Half-wave-resonator	ion, cavity, SRF, cryomodule	266
	M. Ge, F. Furuta, J.E. Gillette, T. Gruber, S.W. Hartman, M. Liepe, T.I. O'Connell, P.J. Pamel, P. Quigley, J. Sears, V. Veshcherevich Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA B.H. Choi, J. Joo, J.W. Kim, W.K. Kim, J. Lee, I. Shin IBS, Daejeon, Republic of Korea
	The half-wave-resonators (HWRs) for the RAON project require a slow frequency tuner that can provide >80 kHz tuning range. Cornell University is currently in the process of designing, prototyping, and testing this HWR tuner. In this paper, we present the optimized tuner design, prototype fabrication, test insert preparation, and cryogenic test results. The performance of the tuner is analysed in detail.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-MOPB087
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MOPB089	Characterisation of Magnetic Shielding Material for HL-LHC Crab Cavities	ion, cavity, shielding, ECR	273
	K. Eiler, P. Arpaia, M.C.L. Buzio, O. Capatina, S.A.E. Langeslag, A. Parrella CERN, Geneva, Switzerland P. Arpaia, A. Parrella Naples University Federico II, Science and Technology Pole, Napoli, Italy A. Parrella IT, Lisboa, Portugal N. Templeton STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom
	Funding: CERN, 1211 Geneva 23 To guarantee optimum performance, the crab cavities for the high-luminosity upgrade of CERN's LHC need to be shielded from external magnetic fields. Consequently, they will be enclosed by two layers of magnetic shielding, of which the inner is immersed in superfluid helium at 2 K. A Ni-based high-permeability material with a tailored composition and a designated heat treatment is applied. Its magnetic properties at cryogenic temperature are however not yet fully assessed. Especially the effect of deformation on magnetic properties has not been thoroughly investigated, however strain effects may have severe consequences. A magnetic measurement set-up has been developed, and the magnetic permeability at room temperature and at cryogenic temperatures is evaluated, showing that the maximum relative permeability at 4 K exceeds the design criteria of 100, 000. Measurements of the magnetic permeability after introduction of uniaxial plastic deformation between 0% and 3% are conducted by means of an Epstein frame. Results show that deformation induces significant decrease of the magnetic performance, underlining that particular care must be taken during all stages of handling and operation. *konrad.eiler@cern.ch
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-MOPB089
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TUPB009	High-frequency SRF Cavities	cavity, ion, SRF, ECR	400
	T.E. Oseroff, D.L. Hall, M. Liepe, J.T. Maniscalco Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
	Historically, the frequency of SRF cavities has been limited by cryogenic power dissipation increasing rapidly with frequency, due to the BCS surface resistance having a quadratic dependence on frequency. Now, new SRF surfaces using doped niobium and compound superconductors like Nb3Sn can drastically reduce the BCS part of the surface resistance. The temperature independent part of the surface resistance (residual resistance) can therefore become dominant, and has its own, different frequency dependence. We have developed a model to analyze cryogenic cooling power requirements for SRF cavities as function of operating frequency, temperature, and trapped flux to evaluate the impact of the novel low-loss SRF surfaces on the questions of optimal operating frequency and frequency limit. We show that high-frequency SRF cavities now become a realistic option for future SRF driven accelerators. As the transverse cavity size decreases inversely with respect to its resonant frequency, such high-frequency SRF cavities could greatly reduce cost.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-TUPB009
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TUPB060	Innovative Cryogenic Test Facility for Testing SRF Cavity Series Production	ion, cavity, SRF, operation	520
	L. Bizel-Bizellot, M. Ellis, S.M. Pattalwar, M.D. Pendleton, P.A. Smith, A.E. Wheelhouse STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
	Testing SRF cavities in a vertical cryostat is the first step in qualifying the performance of SRF cavities before being integrated into a cryomodule. The European Spallation Source (ESS) requires 84 high-beta 5 cells, 704 MHz cavities which will be manufactured and qualified for their RF performance in a vertical cryostat at Science and Technology Facility Council (STFC) Daresbury Laboratory (United-kingdom). Taking a conventional approach each vertical test would require a large cryostat demanding more than 7000 litres of liquid helium per test for testing 3 cavities simultaneously. In order to reduce the overall operating cost, we plan to develop an alternative method to divide the liquid helium consumption by 5 by filling liquid helium only in each individual helium vessels enclosing each cavity placed horizontally in the cryostat. Therefore the test is performed in more realistic conditions such as in a cryomodule and reduces the operating time. This also reduces the mass flow-rate to be handled by a factor 10, leading to 2 g/s, thus reducing the size of the associated components such as the 2 K pumps, the safety device, the valves and transfer lines.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-TUPB060
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TUPB104	First Full Cryogenic Test of the SRF Thin Film Test Cavity	ion, cavity, SRF, niobium	644
	R. Valizadeh, L. Bizel-Bizellot, P. Goudket, L. Gurran, O.B. Malyshev, N. Pattalwar, S.M. Pattalwar STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom G. Burt, L. Gurran Lancaster University, Lancaster, United Kingdom G. Burt, P. Goudket, O.B. Malyshev, S.M. Pattalwar, R. Valizadeh Cockcroft Institute, Warrington, Cheshire, United Kingdom L. Gurran Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
	A test cavity that uses RF chokes, rather than a physical seal, to contain the field is a promising method of SRF sample testing, especially in thin films research where the rate of sample production far outstrips that of full SRF characterisation. Having the sample and cavity physically separate reduces the complexity involved in changing samples - major causes of low throughput rate and high running costs for other test cavities - and also allows direct measurement of the RF power dissipated in the sample via power calorimetry. Choked test cavities operating at 7.8 GHz with three RF chokes have been designed and tested at Daresbury Laboratory. As part of the commissioning of this system, we performed the first full SRF test with a bulk Nb sample and we verified that the system would perform as required for future superconducting thin film sample tests.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-TUPB104
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WEYA05	Progress Toward 2 K High Performance Half-wave Resonators and Cryomodule	ion, cavity, cryomodule, SRF	692
	Z.A. Conway, B.M. Guilfoyle, M. Kedzie, M.P. Kelly, T. Reid ANL, Argonne, Illinois, USA H. Guo IMP/CAS, Lanzhou, People's Republic of China
	Funding: This material is based upon work supported by the U.S. DOE, Office of Science's Office of Nuclear Physics and Office of High Energy Physics, contract numbers DE-AC02-06CH11357 and DE-AC02-76CH03000. Argonne National Laboratory is implementing a novel 2.0 K superconducting cavity cryomodule operating at 162.5 MHz. This cryomodule is designed for the acceleration of 2 mA H-/proton beams from 2.1 to 10.3 MeV as part of the Fermilab Proton Improvement Project-II (PIP-II). The 2.0 K cryomodule is comprised of 8 half-wave cavities operated in the continuous wave mode with 8 superconducting magnets, one in front of each cavity. In this paper we will review recent cavity results which demonstrate continuous-wave operated cavities with low-field residual resistances of 2.5 nΩ which achieve peak surface fields up to 134 MV/m and 144 mT, electric and magnetic respectively, with field emission onset fields greater than 70 MV/m in the production cavities following the prototyping effort.
	Slides WEYA05 [1.967 MB]
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THYA05	Developments and Progress with ESS Elliptical Cryomodules at CEA-Saclay and IPN-orsay	ion, cavity, cryomodule, vacuum	729
	F. Peauger, C. Arcambal, F. Ardellier, S. Berry, P. Bosland, A. Bouygues, E. Cenni, J.-P. Charrier, G. Devanz, F. Éozénou, A. Gaget, D. Gevaert, A. Gomes, T. Hamelin, X. Hanus, P. Hardy, V.M. Hennion, T.J. Joannem, C. Marchand, O. Piquet, J.P. Poupeau, B. Renard, P. Sahuquet, T. Trublet CEA/DRF/IRFU, Gif-sur-Yvette, France C. Darve ESS, Lund, Sweden G. Olivier IPN, Orsay, France
	CEA Saclay in collaboration with IPN Orsay is in charge of the ESS elliptical cavities cryomodule design, prototyping and series production. Two cryomodule prototypes are being developed and will be tested at CEA Saclay before starting the series production. The main cryomodule design features are first reminded. We present the cavities and couplers test results and the achieved assembly sequences of the first medium beta cavities cryomodule demonstrator M-ECCTD. The progress on the preparation of the CEA cryomodule test station is given. The procurement status and development plan of the second high beta demonstrator H-ECCTD are also reported. Finally we give the components procurement progress and the assembly strategy of the 30 series cry-omodules to be integrated at CEA before delivery to ESS at Lund.
	Slides THYA05 [11.226 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-THYA05
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THPB026	Investigation of the Effect of Strategically Selected Grain Boundaries on Superconducting Properties of SRF Cavity Niobium	ion, niobium, cavity, SRF	787
	M. Wang, T.R. Bieler Michigan State University, East Lansing, Michigan, USA S. Balachandran, P.J. Lee NHMFL, Tallahassee, Florida, USA S. Chetri, A. Polyanskii ASC, Tallahassee, Florida, USA C. Compton FRIB, East Lansing, Michigan, USA
	Funding: Research supported by DOE/OHEP contracts DE-SC0009962, DE-SC0009960, NSF-DMR-1157490, and the State of Florida. High purity Nb is commonly used for fabricating SRF cavities due to its high critical temperature and its formability. However, microstructural defects such as dislocations and grain boundaries in niobium can serve as favorable sites for pinning centers of magnetic flux that can degrade SRF cavity performance. In this study, two bi-crystal niobium samples extracted from strategically selected grain boundaries were investigated for the effect of grain misorientation on magnetic flux behavior. Laue X-ray and EBSD-OIM crystallographic analyses were used to characterize grain orientations and orientation gradients. Cryogenic Magneto-Optical Imaging (MOI) was used to directly observe magnetic flux penetration at about 5-8 K. Flux penetration was observed along one of the grain boundaries, as well as along a low angle boundary that was not detected prior to MOI imaging. Hydride scars on the sample surface after MOI were examined using atomic force microscopy (AFM) analysis. The relationships between dislocation content, cryo-cooling, flux penetration and grain boundaries are examined.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-THPB026
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THPB058	R&D of Thin Film Coating on Superconductors	ion, controls, embedded, FPGA	877
	Y. Iwashita, H. Tongu Kyoto ICR, Uji, Kyoto, Japan H. Hayano, T. Kubo, T. Saeki KEK, Ibaraki, Japan M. Hino Kyoto University, Research Reactor Institute, Osaka, Japan H. Oikawa Utsunomiya University, Utsunomiya, Japan
	Funding: This research is partially supported by Grant-in-Aid for Exploratory Research JSPS KAKENHI Grant Number 26600142, and Photon and Quantum Basic Research Coordinated Development Program from the MEXT. Multilayer thin film coating is a promising technology to enhance performance of superconducting cavities. Until recently, principal parameters to achieve the sufficient performance had not been known, such as the thickness of each layer. We proposed a method to deduce a set of the parameters to exhibit a good performances. In order to verify the scheme, we are trying to make some experiments on the subject at Kyoto. The sample preparation and the test setup for the measurement apparatus will be discussed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-THPB058
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Paper

Title

Other Keywords

Page

MOPB035

Cryogenic Probe Station at Old Dominion University Center for Accelerator Science

ion, cavity, SRF, niobium

128

J. Makita, J.R. Delayen, A.V. Gurevich
ODU, Norfolk, Virginia, USA
G. Ciovati
JLab, Newport News, Virginia, USA

With a growing effort in research and development of an alternative material to bulk Nb for a superconducting radiofrequency (SRF) cavity, it is important to have a cost effective method to benchmark new materials of choice. At Old Dominion University's Center for Accelerator Science, a cryogenic probe station (CPS) will be used to measure the response of superconductor samples under RF fields. The setup consists of a closed-cycle refrigerator for cooling a sample wafer to a cryogenic temperature, a superconducting magnet providing a field parallel to the sample, and DC probes in addition to RF probes. The RF probes will extract a quality factor from a sample patterned in a coplanar waveguide resonator structure on a 2' wafer. From the measured quality factor, the surface resistance and the penetration depth as a function of temperature and magnetic field will be calculated. This paper will discuss the design and measurement procedures of the current CPS setup.

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reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-MOPB035

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MOPB037

Progress of the 2x4-Cell Superconducting Accelerator for the CAEP THz-FEL Facility

ion, cavity, pick-up, cryomodule

134

K. Zhou, C.L. Lao, M. Li, X. Luo, L.J. Shan, X. Shen, H. Wang, X. Yang
CAEP/IAE, Mianyang, Sichuan, People's Republic of China
X.Y. Lu
PKU, Beijing, People's Republic of China

The high average power THz radiation facility is now under construction in China Academy of Engineering Physics. The superconducting accelerator is one of the most important components for this facility, including two 4-Cell TESLA superconducting radio frequency cavities. The designed effective field gradients for both cavities are 10^-12 MV/m. This paper will present the progress of the 2x4-cell superconducting accelerator, mainly including its construction and cryogenic test in Chengdu. At 2 K state, the cryomodule works smoothly and stably. The effective field gradients of both cavities have achieved 10 MV/m. Further beam loading experiments are now in progress.

Poster MOPB037 [5.124 MB]

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MOPB045

JLab New Injector Cryomodule Design, Fabrication and Testing

cavity, ion, cryomodule, HOM

158

G. Cheng, M.A. Drury, J.F. Fischer, R. Kazimi, K. Macha, H. Wang
JLab, Newport News, Virginia, USA

Funding: U.S. DOE Contract No. DE-AC05-06OR23177.
A new Injector Cryomodule (INJ CM) aimed to replace the existing Quarter Cryomodule in the CEBAF tunnel has been developed at Jefferson Lab (JLab). It is sched-uled to be first tested in the Cryomodule Test Facility (CMTF) for module performance then the Upgraded Injector Test Facility (UITF) with electron beam. This new cryomodule, hosting a 2-cell and 7-cell cavity, is designed to boost the electron energy from 200 keV to 5 MeV and permit 380 uA - 1.0 mA of beam current. The 2-cell cavity is a new design whereas the 7-cell cavity is refurbished from a low loss cavity from the retired JLab Renascence Cryomodule. The INJ CM adopts quite a few designs from the JLab 12 GeV Upgrade Cryomodule (C100). Examples of this include having the cold mass hung from a spaceframe structure by use of axial and transverse Nitronic rods, cavities to be tuned by scissor-jack style tuners and the end cans are actually modified from C100 style end cans. However, this new INJ CM is not a quarter of the C100 Cryomodule. This paper focuses on the major design features, fabrication and alignment process and testing of the module and its components.
Authored by Jefferson Science Associates, LLC. The U.S. Government retains a non-exclusive, paid-up, irrevocable, world-wide license to publish or reproduce this manuscript for Government purposes.

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MOPB069

Design of the High Power Input Coupler for CEPC Main Ring Cavity *

ion, cavity, coupling, vacuum

216

T.M. Huang, Q. Ma, J.Y. Zhai
IHEP, Beijing, People's Republic of China
K.X. Gu
Institute of High Energy Physics (IHEP), Chinese Academy of Sciences, Beijing, People's Republic of China

The main ring cavities of CEPC project are two-cell el-liptical superconducting cavities operating at 650 MHz in CW mode. Each cavity equips with one high power input coupler and each coupler has to deliver at least 300 kW of CW RF power to the beam. A variable coupling from 10⁵ to 2·10⁶ is required to meet different operation modes. Considering the cavities working with high quali-ty factor up to 2·10¹⁰, the coupler assembled with cavity in class 10 clean room is strongly recommended to protect the cavity from contamination. Also, low cryogenic heat loss is one of the important issues for a large scale CW operation machine. Some of the above requirements should be compromise. Therefore, it's a big challenge to design a high power input coupler fulfilling the above requirements simultaneously. A new coupler that employs 75 Ω coaxial line sections, a planar ceramic disk win-dow, a coaxial to waveguide transition and a coupling adjusting actuator has been designed. In this paper, the RF design, thermal stress analysis and preliminary me-chanical design of the coupler are presented.

Poster MOPB069 [0.735 MB]

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MOPB087

Frequency Tuner Development and Testing at Cornell for the RAON Half-wave-resonator

ion, cavity, SRF, cryomodule

266

M. Ge, F. Furuta, J.E. Gillette, T. Gruber, S.W. Hartman, M. Liepe, T.I. O'Connell, P.J. Pamel, P. Quigley, J. Sears, V. Veshcherevich
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
B.H. Choi, J. Joo, J.W. Kim, W.K. Kim, J. Lee, I. Shin
IBS, Daejeon, Republic of Korea

The half-wave-resonators (HWRs) for the RAON project require a slow frequency tuner that can provide >80 kHz tuning range. Cornell University is currently in the process of designing, prototyping, and testing this HWR tuner. In this paper, we present the optimized tuner design, prototype fabrication, test insert preparation, and cryogenic test results. The performance of the tuner is analysed in detail.

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reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-MOPB087

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MOPB089

Characterisation of Magnetic Shielding Material for HL-LHC Crab Cavities

ion, cavity, shielding, ECR

273

K. Eiler, P. Arpaia, M.C.L. Buzio, O. Capatina, S.A.E. Langeslag, A. Parrella
CERN, Geneva, Switzerland
P. Arpaia, A. Parrella
Naples University Federico II, Science and Technology Pole, Napoli, Italy
A. Parrella
IT, Lisboa, Portugal
N. Templeton
STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom

Funding: CERN, 1211 Geneva 23
To guarantee optimum performance, the crab cavities for the high-luminosity upgrade of CERN's LHC need to be shielded from external magnetic fields. Consequently, they will be enclosed by two layers of magnetic shielding, of which the inner is immersed in superfluid helium at 2 K. A Ni-based high-permeability material with a tailored composition and a designated heat treatment is applied. Its magnetic properties at cryogenic temperature are however not yet fully assessed. Especially the effect of deformation on magnetic properties has not been thoroughly investigated, however strain effects may have severe consequences. A magnetic measurement set-up has been developed, and the magnetic permeability at room temperature and at cryogenic temperatures is evaluated, showing that the maximum relative permeability at 4 K exceeds the design criteria of 100, 000. Measurements of the magnetic permeability after introduction of uniaxial plastic deformation between 0% and 3% are conducted by means of an Epstein frame. Results show that deformation induces significant decrease of the magnetic performance, underlining that particular care must be taken during all stages of handling and operation.
*konrad.eiler@cern.ch

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reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-MOPB089

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TUPB009

High-frequency SRF Cavities

cavity, ion, SRF, ECR

400

T.E. Oseroff, D.L. Hall, M. Liepe, J.T. Maniscalco
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

Historically, the frequency of SRF cavities has been limited by cryogenic power dissipation increasing rapidly with frequency, due to the BCS surface resistance having a quadratic dependence on frequency. Now, new SRF surfaces using doped niobium and compound superconductors like Nb3Sn can drastically reduce the BCS part of the surface resistance. The temperature independent part of the surface resistance (residual resistance) can therefore become dominant, and has its own, different frequency dependence. We have developed a model to analyze cryogenic cooling power requirements for SRF cavities as function of operating frequency, temperature, and trapped flux to evaluate the impact of the novel low-loss SRF surfaces on the questions of optimal operating frequency and frequency limit. We show that high-frequency SRF cavities now become a realistic option for future SRF driven accelerators. As the transverse cavity size decreases inversely with respect to its resonant frequency, such high-frequency SRF cavities could greatly reduce cost.

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reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-TUPB009

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TUPB060

Innovative Cryogenic Test Facility for Testing SRF Cavity Series Production

ion, cavity, SRF, operation

520

L. Bizel-Bizellot, M. Ellis, S.M. Pattalwar, M.D. Pendleton, P.A. Smith, A.E. Wheelhouse
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom

Testing SRF cavities in a vertical cryostat is the first step in qualifying the performance of SRF cavities before being integrated into a cryomodule. The European Spallation Source (ESS) requires 84 high-beta 5 cells, 704 MHz cavities which will be manufactured and qualified for their RF performance in a vertical cryostat at Science and Technology Facility Council (STFC) Daresbury Laboratory (United-kingdom). Taking a conventional approach each vertical test would require a large cryostat demanding more than 7000 litres of liquid helium per test for testing 3 cavities simultaneously. In order to reduce the overall operating cost, we plan to develop an alternative method to divide the liquid helium consumption by 5 by filling liquid helium only in each individual helium vessels enclosing each cavity placed horizontally in the cryostat. Therefore the test is performed in more realistic conditions such as in a cryomodule and reduces the operating time. This also reduces the mass flow-rate to be handled by a factor 10, leading to 2 g/s, thus reducing the size of the associated components such as the 2 K pumps, the safety device, the valves and transfer lines.

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reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-TUPB060

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TUPB104

First Full Cryogenic Test of the SRF Thin Film Test Cavity

ion, cavity, SRF, niobium

644

R. Valizadeh, L. Bizel-Bizellot, P. Goudket, L. Gurran, O.B. Malyshev, N. Pattalwar, S.M. Pattalwar
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
G. Burt, L. Gurran
Lancaster University, Lancaster, United Kingdom
G. Burt, P. Goudket, O.B. Malyshev, S.M. Pattalwar, R. Valizadeh
Cockcroft Institute, Warrington, Cheshire, United Kingdom
L. Gurran
Cockcroft Institute, Lancaster University, Lancaster, United Kingdom

A test cavity that uses RF chokes, rather than a physical seal, to contain the field is a promising method of SRF sample testing, especially in thin films research where the rate of sample production far outstrips that of full SRF characterisation. Having the sample and cavity physically separate reduces the complexity involved in changing samples - major causes of low throughput rate and high running costs for other test cavities - and also allows direct measurement of the RF power dissipated in the sample via power calorimetry. Choked test cavities operating at 7.8 GHz with three RF chokes have been designed and tested at Daresbury Laboratory. As part of the commissioning of this system, we performed the first full SRF test with a bulk Nb sample and we verified that the system would perform as required for future superconducting thin film sample tests.

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reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-TUPB104

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WEYA05

Progress Toward 2 K High Performance Half-wave Resonators and Cryomodule

ion, cavity, cryomodule, SRF

692

Z.A. Conway, B.M. Guilfoyle, M. Kedzie, M.P. Kelly, T. Reid
ANL, Argonne, Illinois, USA
H. Guo
IMP/CAS, Lanzhou, People's Republic of China

Funding: This material is based upon work supported by the U.S. DOE, Office of Science's Office of Nuclear Physics and Office of High Energy Physics, contract numbers DE-AC02-06CH11357 and DE-AC02-76CH03000.
Argonne National Laboratory is implementing a novel 2.0 K superconducting cavity cryomodule operating at 162.5 MHz. This cryomodule is designed for the acceleration of 2 mA H-/proton beams from 2.1 to 10.3 MeV as part of the Fermilab Proton Improvement Project-II (PIP-II). The 2.0 K cryomodule is comprised of 8 half-wave cavities operated in the continuous wave mode with 8 superconducting magnets, one in front of each cavity. In this paper we will review recent cavity results which demonstrate continuous-wave operated cavities with low-field residual resistances of 2.5 nΩ which achieve peak surface fields up to 134 MV/m and 144 mT, electric and magnetic respectively, with field emission onset fields greater than 70 MV/m in the production cavities following the prototyping effort.

Slides WEYA05 [1.967 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-WEYA05

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THYA05

Developments and Progress with ESS Elliptical Cryomodules at CEA-Saclay and IPN-orsay

ion, cavity, cryomodule, vacuum

729

F. Peauger, C. Arcambal, F. Ardellier, S. Berry, P. Bosland, A. Bouygues, E. Cenni, J.-P. Charrier, G. Devanz, F. Éozénou, A. Gaget, D. Gevaert, A. Gomes, T. Hamelin, X. Hanus, P. Hardy, V.M. Hennion, T.J. Joannem, C. Marchand, O. Piquet, J.P. Poupeau, B. Renard, P. Sahuquet, T. Trublet
CEA/DRF/IRFU, Gif-sur-Yvette, France
C. Darve
ESS, Lund, Sweden
G. Olivier
IPN, Orsay, France

CEA Saclay in collaboration with IPN Orsay is in charge of the ESS elliptical cavities cryomodule design, prototyping and series production. Two cryomodule prototypes are being developed and will be tested at CEA Saclay before starting the series production. The main cryomodule design features are first reminded. We present the cavities and couplers test results and the achieved assembly sequences of the first medium beta cavities cryomodule demonstrator M-ECCTD. The progress on the preparation of the CEA cryomodule test station is given. The procurement status and development plan of the second high beta demonstrator H-ECCTD are also reported. Finally we give the components procurement progress and the assembly strategy of the 30 series cry-omodules to be integrated at CEA before delivery to ESS at Lund.

Slides THYA05 [11.226 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-THYA05

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THPB026

Investigation of the Effect of Strategically Selected Grain Boundaries on Superconducting Properties of SRF Cavity Niobium

ion, niobium, cavity, SRF

787

M. Wang, T.R. Bieler
Michigan State University, East Lansing, Michigan, USA
S. Balachandran, P.J. Lee
NHMFL, Tallahassee, Florida, USA
S. Chetri, A. Polyanskii
ASC, Tallahassee, Florida, USA
C. Compton
FRIB, East Lansing, Michigan, USA

Funding: Research supported by DOE/OHEP contracts DE-SC0009962, DE-SC0009960, NSF-DMR-1157490, and the State of Florida.
High purity Nb is commonly used for fabricating SRF cavities due to its high critical temperature and its formability. However, microstructural defects such as dislocations and grain boundaries in niobium can serve as favorable sites for pinning centers of magnetic flux that can degrade SRF cavity performance. In this study, two bi-crystal niobium samples extracted from strategically selected grain boundaries were investigated for the effect of grain misorientation on magnetic flux behavior. Laue X-ray and EBSD-OIM crystallographic analyses were used to characterize grain orientations and orientation gradients. Cryogenic Magneto-Optical Imaging (MOI) was used to directly observe magnetic flux penetration at about 5-8 K. Flux penetration was observed along one of the grain boundaries, as well as along a low angle boundary that was not detected prior to MOI imaging. Hydride scars on the sample surface after MOI were examined using atomic force microscopy (AFM) analysis. The relationships between dislocation content, cryo-cooling, flux penetration and grain boundaries are examined.

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reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-THPB026

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THPB058

R&D of Thin Film Coating on Superconductors

ion, controls, embedded, FPGA

877

Y. Iwashita, H. Tongu
Kyoto ICR, Uji, Kyoto, Japan
H. Hayano, T. Kubo, T. Saeki
KEK, Ibaraki, Japan
M. Hino
Kyoto University, Research Reactor Institute, Osaka, Japan
H. Oikawa
Utsunomiya University, Utsunomiya, Japan

Funding: This research is partially supported by Grant-in-Aid for Exploratory Research JSPS KAKENHI Grant Number 26600142, and Photon and Quantum Basic Research Coordinated Development Program from the MEXT.
Multilayer thin film coating is a promising technology to enhance performance of superconducting cavities. Until recently, principal parameters to achieve the sufficient performance had not been known, such as the thickness of each layer. We proposed a method to deduce a set of the parameters to exhibit a good performances. In order to verify the scheme, we are trying to make some experiments on the subject at Kyoto. The sample preparation and the test setup for the measurement apparatus will be discussed.

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reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-THPB058

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