Author: Ikeda, H.
Paper Title Page
WEYAT0102 Mitigation of Electron Cloud Effect in the SuperKEKB Positron Ring 146
 
  • Y. Suetsugu, H. Fukuma, H. Hisamatsu, H. Ikeda, T. Ishibashi, K. Kanazawa, K. Ohmi, K. Shibata, M. Shirai, S. Terui, M. Tobiyama
    KEK, Ibaraki, Japan
  • Y.M. Lee
    Sokendai, Ibaraki, Japan
 
  One critical issue for the SuperKEKB is the electron cloud effect (ECE) in the positron ring, and various countermeasures had been prepared before starting the commissioning. The ECE, however, was observed during phase-1 commissioning (2016) caused by the electron cloud in the beam pipes at drift spaces of the ring, which had antechambers and a TiN-film coating. Permanent magnets and solenoids to generate magnetic fields in the beam direction were attached to the beam pipes as additional countermeasures before the next phase-2 commissioning (2018). Consequently, the threshold of the current linear density for exciting the ECE increased by a factor of at least 2. During Phase-3 commissioning (2019), it was confirmed that the threshold was over 0.53 mA/bunch/RF bucket, and we have observed no clear evidence of ECE in the usual operation up to now. The effectiveness of the ante-chambers and TiN film coating of the real beam pipe was reevaluated. The present ante-chambers were found to be less effective than expected with regard to reducing the number of photoelectrons in the beam channel. Here we will summarize the mitigation techniques used in the SuperKEKB and the results so far.  
slides icon Slides WEYAT0102 [7.521 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-eeFACT2022-WEYAT0102  
About • Received ※ 22 September 2022 — Revised ※ 04 February 2023 — Accepted ※ 08 February 2023 — Issue date ※ 11 February 2023
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WEZAS0202 SuperKEKB Beam Instabilities Challenges and Experience 202
 
  • H. Ikeda, H. Fukuma, T. Kobayashi, T. Mimashi, T.M. Mitsuhashi, G. Mitsuka, S. Sasaki, M. Tobiyama
    KEK, Ibaraki, Japan
 
  KEKB was upgraded from 2011 over 5 years in order to increase the luminosity and started SuperKEKB commissioning in 2018 after the test operation. In order to cope with large beam currents and small beam sizes, various updates have been applied to the beam instrumentation system. This talk summarizes the performance of beam instrumentation in SuperKEKB Phase-III and challenges to it.  
slides icon Slides WEZAS0202 [7.068 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-eeFACT2022-WEZAS0202  
About • Received ※ 30 November 2022 — Revised ※ 03 February 2023 — Accepted ※ 08 February 2023 — Issue date ※ 13 February 2023
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