Keyword: accelerating-gradient
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MOP027 Study on Nitrogen Infusion using KEK New Furnace cavity, injection, SRF, vacuum 95
 
  • K. Umemori, E. Kako, T. Konomi, S. Michizono, H. Sakai
    KEK, Ibaraki, Japan
  • T. Okada
    Sokendai, Ibaraki, Japan
  • J. Tamura
    JAEA/J-PARC, Tokai-mura, Japan
 
  KEK has been carried out high-Q/high-G R&D, to realize high performance of SRF cavities toward ILC. KEK constructed a new furnace, which is dedicated for N-infusion studies. We performed more than 10 times of N-infusion trials using 1.3 GHz single-cell cavities. Some results showed better Q-values up to high field, however, some results showed degraded Q-E slopes probably due to contamination. Improvement of accelerating gradient is not observed at moment. We have tried to clean the furnace and Nitrogen injection line to reduce the effect of contamination. Details of procedures of N-infusion, results of vertical tests, condition of the furnace including RGA spectrum and Nb sample analysis results are shown.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-MOP027  
About • paper received ※ 04 July 2019       paper accepted ※ 04 July 2019       issue date ※ 14 August 2019  
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MOP039 Nitrogen Doping Studies of Superconducting Cavities at Peking University cavity, niobium, superconducting-cavity, 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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TUP020 Statistical Analysis of the 120°C Bake Procedure of Superconducting Radio Frequency Cavities cavity, FEL, SRF, niobium 444
 
  • L. Steder, D. Reschke
    DESY, Hamburg, Germany
 
  DESY is and was very active in R&D related to SRF cavities. Many single and nine cell cavities with different surface treatment histories were tested vertically. Results of these cold tests are accelerating gradient and quality factor of the cavities. Using the large number of available datasets the parameters of the 120°C bake procedure, which is applied to avoid high-field Q-slope, are analysed. The impact of different durations and temperatures on accelerating gradient, quality factor and residual resistance is studied in detail and is compared to results obtained with the recently proposed procedure of modified low temperature bake. For this procedure additional four hours at temperatures around 75°C are implemented before the standard bake at about 120°C. Since the claim is, that cavities treated with such a modified procedure achieve extra-ordinary large accelerating gradients it is a very interesting research field for the European XFEL continuous wave mode upgrade. For this purpose cavities with high quality factors are needed, but in addition large maximal accelerating fields are required to maintain high energies in the pulsed operation mode of the accelerator.  
poster icon Poster TUP020 [0.747 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-TUP020  
About • paper received ※ 21 June 2019       paper accepted ※ 30 June 2019       issue date ※ 14 August 2019  
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TUP054 How Is Flux Expulsion Affected by Geometry: Experimental Evidence and Model cavity, niobium, experiment, SRF 555
 
  • D. Longuevergne
    IPN, Orsay, France
 
  Measurements of magnetic sensitivity to trapped flux on several type of cavity geometries have been performed at IPNO showing a clear geometrical effect. Magnetic sensitivity depends not only on material quality but also on the cavity geometry and on the residual magnetic field orientation. A presentation of experimental data will be done. These will be as well compared to the theoretical magnetic sensitivities calculated thanks to a simple Labview routine  
poster icon Poster TUP054 [1.312 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-TUP054  
About • paper received ※ 03 July 2019       paper accepted ※ 04 July 2019       issue date ※ 14 August 2019  
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TUP062 New Insights in the Quench Mechanisms in Nitrogen Doped Cavities cavity, SRF, niobium, factory 592
 
  • D. Bafia, J. Zasadzinski
    IIT, Chicago, Illinois, USA
  • D. Bafia, D.J. Bice, A. Grassellino, O.S. Melnychuk, A.S. Romanenko, D.A. Sergatskov
    Fermilab, Batavia, Illinois, USA
  • D. Gonnella
    SLAC, Menlo Park, California, USA
  • A.D. Palczewski
    JLab, Newport News, Virginia, USA
 
  This paper will cover a systematic study of the quench in nitrogen doped cavities: three cavities were sequentially treated/reset with different doping recipes which are known to produce different levels of quench field. Analysis of mean free path and TMAP coupled with sample analysis reveals new insights on the physics of the premature quench in nitrogen doped cavities; new recipes demonstrate the possibility to increase quench fields well beyond 30 MV/m.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-TUP062  
About • paper received ※ 23 June 2019       paper accepted ※ 02 July 2019       issue date ※ 14 August 2019  
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