Keyword: superconducting-cavity
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MOP039 Nitrogen Doping Studies of Superconducting Cavities at Peking University cavity, niobium, accelerating-gradient, ECR 141
 
  • S. Chen, M. Chen, L.W. Feng, J.K. Hao, L. Lin, K.X. Liu, S.W. Quan, F. Wang, F. Zhu
    PKU, Beijing, People’s Republic of China
 
  Nitrogen doping studies with 1.3 GHz superconducting cavities were carried out at Peking University in recent years. We have realized 4×1010 of high quality factor at 12 MV/m and 2.0 K with large grain single cell cavities by heavy doping. To improve the accelerating gradient of high Q cavities, light doping recipe is adopted. Accelerating gradient is improved to 20 MV/m and the quality factor is larger than 3×1010 at 16 MV/m and 2.0 K for light doped cavities. The nitrogen treatment, test and analysis are presented in this paper.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-MOP039  
About • paper received ※ 21 June 2019       paper accepted ※ 30 June 2019       issue date ※ 14 August 2019  
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TUP010 Mechanical Design and Horizontal Tests of a Dressed 166.6 MHz Quarter-wave β=1 SRF Cavity System cavity, simulation, cryomodule, SRF 408
 
  • X.Y. Zhang, X.R. Hao, D.B. Li, Z.Q. Li, H.Y. Lin, Q. Ma, Z.H. Mi, Q.Y. Wang, P. Zhang
    IHEP, Beijing, People’s Republic of China
 
  Funding: This work has been supported by HEPS-TF project.
A 166.6 MHz quarter-wave β=1 superconducting proof-of-principle cavity has been designed and recently been dressed with a helium jacket, fundamental power coupler and tuner. The cavity was subsequently installed in a modified cryomodule and tested in a horizontal manner at both 4.2 K and 2 K. The helium jacket was successfully developed with a focus on minimizing frequency shift due to helium pressure fluctuation while retaining a reasonable tuning range. The Lorentz force detuning (LFD) and microphonics were also optimized during the design. The df/dp and LFD coefficient were measured to be -3.1 Hz/mbar and -0.8 Hz/(MV/m)2. These are in good agreement with simulations. Future work is mainly to reduce the stiffness of the cavity and further suppress the vibration mode of the inner conductor.
 
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DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-TUP010  
About • paper received ※ 23 June 2019       paper accepted ※ 29 June 2019       issue date ※ 14 August 2019  
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TUP059 Investigation of Trapped Flux Dynamics via DC-Magnetic Quenching cavity, experiment, ECR, SRF 580
 
  • P. Nuñez von Voigt, J. Knobloch, O. Kugeler
    HZB, Berlin, Germany
  • J. Knobloch
    University of Siegen, Siegen, Germany
 
  Trapped magnetic flux increases the surface resistance in superconducting radio-frequency cavities. A better understanding of its behaviour could help to develop a method of expelling trapped flux from the superconducting surface. Using a superconducting coil with ferrite core attached to a 3 GHz sample Niobium cavity fully immersed in liquid Helium, we were able to subject the cavity walls to unusually large magnetic fields (estimated > 150 mT) and create magnetic quenches. With Fluxgate sensors attached in three spatial directions inside the cavity, we were able to monitor the quench dynamics and extract parameters of the flux dynamics from the hysteretic behaviour of the measured fields resulting from the applied coil current. First results of manipulation of the trapped flux with high magnetic fields are presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-TUP059  
About • paper received ※ 24 June 2019       paper accepted ※ 05 July 2019       issue date ※ 14 August 2019  
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WETEB7 A Ferroelectric Fast Reactive Tuner for Superconducting Cavities cavity, controls, linac, experiment 781
 
  • N.C. Shipman, J. Bastard, M.R. Coly, F. Gerigk, A. Macpherson, N. Stapley
    CERN, Geneva, Switzerland
  • I. Ben-Zvi
    BNL, Upton, New York, USA
  • G. Burt, A. Castilla
    Lancaster University, Lancaster, United Kingdom
  • C.-J. Jing, A. Kanareykin
    Euclid TechLabs, LLC, Solon, Ohio, USA
  • S. Kazakov
    Fermilab, Batavia, Illinois, USA
  • E. Nenasheva
    Ceramics Ltd., St. Petersburg, Russia
 
  A prototype FerroElectric Fast Reactive Tuner (FE-FRT) for superconducting cavities has been developed, which allows the frequency to be controlled by application of a potential difference across a ferroelectric residing within the tuner. This technique has now become practically feasible due to the recent development of a new extremely low loss ferroelectric material. In a world first, CERN has tested the prototype FE-FRT with a superconducting cavity, and frequency tuning has been successfully demonstrated. This is a significant first step in the development of an entirely new class of tuner. These will allow electronic control of cavity frequencies, by a device operating at room temperature, within timescales that will allow active compensation of microphonics. For many applications this could eliminate the need to use over-coupled fundamental power couplers, thus significantly reducing RF amplifier power.  
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DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-WETEB7  
About • paper received ※ 23 June 2019       paper accepted ※ 30 June 2019       issue date ※ 14 August 2019  
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THP072 Development of HOM Absorbers for CW Superconducting Cavities in Energy Recovery Linac HOM, cavity, linac, SRF 1060
 
  • T. Ota, S. Nakamura, K. Sato, M. Takasaki
    Toshiba Energy Systems & Solutions Corporation, Keihin Product Operations, Yokohama, Japan
  • E. Kako, T. Konomi, H. Sakai, K. Umemori
    KEK, Ibaraki, Japan
  • A. Miyamoto
    Toshiba, Yokohama, Japan
 
  Higher Order Modes (HOM) absorbers for superconducting cavities have been developing at TOSHIBA in collaboration with High Energy Accelerator Research Organization (KEK) since 2015. A new prototype HOM absorber for 1.3 GHz 9-cell superconducting cavity was fabricated. An AlN lossy dielectrics cylinder was brazed with a thin copper plate, and the cool-down tests by nitrogen gas was carried out. The copper plate and a copper cylinder were joined by electron beam welding. SUS flanges were electron beam welded to both ends of the copper cylinder to fabricate a whole prototype HOM absorber. Fabrication process of the prototype HOM absorber will be presented in this paper.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-THP072  
About • paper received ※ 21 June 2019       paper accepted ※ 03 July 2019       issue date ※ 14 August 2019  
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THP075 Development of a 166.6 MHz Digital LLRF System for HEPS-TF Project cavity, LLRF, controls, low-level-rf 1073
 
  • Q.Y. Wang, J.P. Dai, T.M. Huang, D.B. Li, H.Y. Lin, Z.H. Mi, P. Zhang
    IHEP, Beijing, People’s Republic of China
 
  A 166.6 MHz superconducting RF system has been proposed for the High Energy Photon Source (HEPS), a 6 GeV kilometer-scale light source. A 166.6MHz digital low-level RF system for HEPS-TF project has been developed firstly. And the digital low-level RF system has been successfully applied to the horizontal high power test of 166.6MHz superconducting cavity. The cavity field stability has been successfully achieved about ±0.03% (pk-pk) in amplitude and ±0.02 degree (pk-pk) in phase while the cavity field voltage is up to 1.2MV. It can meet the field stability requirements towards ±0.1% in ampli-tude and ±0.1 degree in phase of HEPS project. Further study and optimization of the system is under way.  
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DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-THP075  
About • paper received ※ 29 June 2019       paper accepted ※ 30 June 2019       issue date ※ 14 August 2019  
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THP086 Preliminary Design of Superconducting Cavity Test Platform in CSNS Campus cavity, cryomodule, SRF, controls 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 icon 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 cavity, cryogenics, vacuum, SRF 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 icon 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 cavity, controls, GUI, interface 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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