Author: Okada, T.
Paper Title Page
TUPFAV002 Calibration of SRF Cavity Voltage by Measurement of Synchrotron Frequency in SuperKEKB 376
 
  • M. Nishiwaki, K. Akai, T. Furuya, T. Kobayashi, S. Mitsunobu, Y. Morita, T. Okada
    KEK, Ibaraki, Japan
 
  Eight SRF cavity modules, which have been operated in KEKB for more than ten years, are stably operating also in SuperKEKB. As for calibration of the cavity voltage Vc, non-negligible discrepancy was observed between the results obtained from two different methods: one is using external Q value (Qext) of pickup ports, and the other is using loaded Q value (QL) of the cavities. The discrepancy comes from inaccuracy of power measurement in high power RF system and uncertainty of the Qext or QL values. In order to solve the discrepancy by improving the accuracy of the calibration for each individual cavity, we investigated a method by measuring synchrotron frequency fs of stored beam. With this method, Vc calibration can be performed without affected by inaccuracy of high-power measurement or uncertainty of the Qext or QL values. The fs measurement studies were carried out in SuperKEKB. With these studies, Vc calibration was obtained with a high accuracy of about 1%. The results are applied to the SuperKEKB operation.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-TUPFAV002  
About • Received ※ 21 June 2021 — Revised ※ 13 August 2021 — Accepted ※ 21 August 2021 — Issue date ※ 14 October 2021
Cite • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
SUPCAV008 Design and Construction of Nb3Sn Vapor Diffusion Coating System at KEK 23
 
  • K. Takahashi, T. Okada
    Sokendai, Ibaraki, Japan
  • H. Ito, E. Kako, T. Konomi, H. Sakai, K. Umemori
    KEK, Ibaraki, Japan
 
  Vapor diffusion Nb3Sn coating system was developed at KEK. At most 1.3GHz 3-cell cavity can be coat with the coating system. The coating system consists of a coating chamber made of Nb, a vacuum furnace for heating the Nb chamber, and a heating device of Tin in the crucible. The Nb chamber vacuum and the furnace vacuum are isolated to prevent contamination from the furnace. There is a heating device for increasing Tin vapor pressure. In this presentation, the design and construction of the coating system are reported.  
poster icon Poster SUPCAV008 [0.981 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-SUPCAV008  
About • Received ※ 21 June 2021 — Accepted ※ 18 November 2021 — Issue date; ※ 11 April 2022  
Cite • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
SUPCAV009 First Nb3Sn Coating and Cavity Performance Result at KEK 27
 
  • K. Takahashi, T. Okada
    Sokendai, Ibaraki, Japan
  • H. Ito, E. Kako, T. Konomi, H. Sakai, K. Umemori
    KEK, Ibaraki, Japan
 
  At KEK, Nb3Sn vapor diffusion R&D for High-Q has just started. We have performed Nb3Sn coating on niobium samples and characterized these samples. We optimized the cavity coating parameter from the result of characterized samples. After optimizing the parameter, we have performed Nb3Sn coating on a TESLA-like single-cell Nb cavity and measured cavity performance in vertical tests. This presentation presents the result of the cavity coating and performance results.  
poster icon Poster SUPCAV009 [1.477 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-SUPCAV009  
About • Received ※ 21 June 2021 — Accepted ※ 18 March 2022 — Issue date; ※ 16 May 2022  
Cite • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
TUOFDV02
Observation of Precise Distribution of Trapped Magnetic Flux Due to Quench by M&T Mapping System  
 
  • T. Okada
    Sokendai, Ibaraki, Japan
  • E. Kako, M. Masuzawa, H. Sakai, R. Ueki, K. Umemori
    KEK, Ibaraki, Japan
  • P. Pizzol, A. Poudel, T. Tajima
    LANL, Los Alamos, New Mexico, USA
 
  This study focused on the flux trapping of the superconducting cavity by measuring changes in the spatial magnetic field distribution for the Nb single-cell cavity using the magnetic field and temperature mapping system. The different external magnetic fields were applied when the cavity was vertically tested. The differences of magnetic field distribution were compared before and after flux trapping caused by quenches. The magnetic field mapping measured the magnetic field, including 3 axial directions, outside the equator of the cavity. Moreover, the local heating generated by the magnetic flux trapping was observed locally using temperature mapping. The result shows that the changes in the magnetic field distribution have the magnetic field components towards the quench location. In this presentation, the detail of experiments and results of the change of the magnetic field distribution and the local heating will be presented.  
Cite • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)