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Title Observation of Pressure Bursts in the SuperKEKB Positron Ring
  • S. Terui, H. Hisamatsu, T. Ishibashi, K. Kanazawa, K. Shibata, M. Shirai, Y. Suetsugupresenter
    KEK, Ibaraki, Japan
Abstract The SuperKEKB is an electron-positron collider with asymmetric energies in KEK aiming an extremely high luminosity of 8x10³⁵ cm⁻² s⁻¹ using a nano-beam scheme. In the Phase 1 commissioning from February to June, 2016, the vacuum system of the main ring worked well as a whole at stored beam currents of approximately 1 A. However, the localized pressure bursts accompanied by beam losses were observed in the positron ring. The beam loss monitors triggered beam aborts, and the phenomena has became an obstacle to the beam commissioning. These pressure bursts were frequently observed from the early stage of the commissioning. Most of the pressure bursts occurred near or inside of aluminum-alloy beam pipes in dipole magnets, which have grooved surface at the top and bottom sides. The various observations indicates that the most probable cause of this phenomenon was the collision between the dusts dropped from the grooves and the circulating positron beam. We report the properties and the probable causes of the pressure bursts, and the possible mitigation methods. Some results of the countermeasures taken prior to the ongoing Phase-2 commissioning will be also presented.
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Conference IPAC2018, Vancouver, BC, Canada
Series International Particle Accelerator Conference (9th)
Proceedings Link to full IPAC2018 Proccedings
Session MC7 Poster Session
Date 02-May-18   16:00–17:30
Main Classification 07 Accelerator Technology
Sub Classification T14 Vacuum Technology
Keywords MMI, positron, luminosity, electron, operation
Publisher JACoW Publishing, Geneva, Switzerland
Editors Shane Koscielniak (TRIUMF, Vancouver, BC, Canada); Todd Satogata (JLab, Newport News, VA, USA); Volker RW Schaa (GSI, Darmstadt, Germany); Jana Thomson (TRIUMF, Vancouver, BC, Canada)
ISBN 978-3-95450-184-7
Published June 2018
Copyright © 2018 by JACoW, Geneva, Switzerland     CC-BY Creative Commons License
cc Creative Commons Attribution 3.0