Author: Egi, M.
Paper Title Page
TUPO070 Design and Commissioning of KEK New Vacuum Furnace for SRF Cavity Development 496
  • K. Umemori, M. Egi, E. Kako, T. Konomi, S. Michizono, H. Sakai
    KEK, Ibaraki, Japan
  Recently new techniques such as Nitrogen-doping and Nitrogen-infusion have been developed to improve performance of SRF (Superconducting RF) cavities. We purchased a new vacuum furnace, which is key to realize these techniques. Cleanness of the furnace is most important issue. The furnace has a cryo-pump and whole of vacuum system is oil-free system. Target vacuum level after cooling down is 1x10-6 Pa. Heater, reflectors and support table were made from Molybdenum to avoid contamination during heat treatment. Metal gaskets are used for all vacuum seals, except big doors. Maximum operation temperature is 1150 degree C. Size is around 1 m diameter and 2m long for a 1.3 GHz 9-cell cavity. Entrance of furnace is covered by a clean booth. The furnace was fabricated, assembled at KEK COI building and commissioned this year. After several burning runs, target vacuum pressure was achieved after cooling down to room temperature. Design of the furnace and performance during commissioning runs are presented.  
DOI • reference for this paper ※  
About • paper received ※ 19 September 2018      issue date ※ 18 January 2019  
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TUPO071 Study on Nitrogen Infusion for 1.3 GHz SRF Cavities Using J-PARC Furnace 499
  • K. Umemori, T. Dohmae, M. Egi, Y. Hori, E. Kako, T. Konomi, S. Michizono, T. Saeki, H. Sakai, Y. Yamamoto
    KEK, Ibaraki, Japan
  • J. Kamiya
    JAEA/J-PARC, Tokai-mura, Japan
  • S. Kurosawa, K. Takeishi
    JAEA, Ibaraki-ken, Japan
  • T. Okada
    Sokendai, Ibaraki, Japan
  Nitrogen infusion (N-infusion) is new surface treatment technique for niobium SRF (Superconducting RF) cavities. After cooling down from 800 degree C heat treatment, a vacuum furnace and cavities are kept 120 degree C, 48 hours with about 3 Pa Nitrogen. Improvement of Q-value and accelerating gradient is expected. We used J-PARC furnace, since N-infusion procedure requires clean vacuum furnace. It has a cryo-pump and turbo molecular pumps and its vacuum system is oil-free system. Six times of N-infusion tests were carried out, while changing vacuum condition, N-infusion temperature, Nitrogen pressure, niobium material and so on. Niobium caps were mounted on cavities to avoid contaminations on inner surfaces. Some of trials were successful and vertical test results showed improvement of Q-values and accelerating gradient. However, some of them were not. Most of bad cases showed degradation of Q-values above 5 MV/m. Details of heat treatment procedure including N-infusion and vertical test results are shown in this presentation.  
DOI • reference for this paper ※  
About • paper received ※ 20 September 2018      issue date ※ 18 January 2019  
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