Sudden Lifetime Drop Phenomena and their Effective Cures in PF-ring and PF-AR
- Accelerator Laboratory, High Energy Accelerator Research Organization (KEK), 1-1 Oho, Tsukuba, Ibaraki 305-0801 (Japan)
In PF-ring and PF-AR, sudden drops in the electron beam lifetime, which are attributed to dust trapping, were frequently observed after extensive renewals of the storage rings. The reduced-lifetime state sometimes lasts for a few hours, and the mitigation of this problem was strongly demanded for stable user operations. Since a major source of dust particles was thought to be a distributed ion pump (DIP), we attempted switching the DIPs off during user operations in both the rings. As a result, occurrence of the lifetime drops was almost completely suppressed during single-bunch mode in PF-ring, while the occurrence frequency was reduced by only 38% in PF-AR. We found that the lifetime drops were sometimes accompanied by a transient increase in the vacuum pressure at some discharge-prone devices. Based on the hypothesis that the harmful dust could be generated by an electric discharge in vacuum, we attempted the conditioning of these devices in PF-AR by storing 25% higher current than usual. By combination of the DIP-OFF operation and the high-current conditioning, the occurrence frequency of the lifetime drops in PF-AR was reduced by no less than 67%.
- OSTI ID:
- 21410300
- Journal Information:
- AIP Conference Proceedings, Vol. 1234, Issue 1; Conference: SRI 2009: 10. international conference on radiation instrumentation, Melbourne (Australia), 27 Sep - 2 Oct 2009; Other Information: DOI: 10.1063/1.3463277; (c) 2010 American Institute of Physics; ISSN 0094-243X
- Country of Publication:
- United States
- Language:
- English
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