title: Development of bellows and gate valves with a comb-type rf shield for high-current accelerators: four-year beam test at KEK B-Factory.
abstract: Since a comb-type rf shield was proposed in 2003 as a rf shield for future high-intensity accelerators, various types of bellow chambers and gate valves with this rf shield have been installed in the KEK B-Factory rings in series and tested with beams. Through beam tests to check the performance, a structural simplification has been tried in parallel. The temperatures of the bellow corrugations decreased by a factor of 3-6 compared to those with a conventional finger-type rf shield in most cases. The temperatures of the body of the gate valves also decreased by a factor of 2-5. These results demonstrated the availability of the comb-type rf shield. Although a discharge was observed in one simplified model, the latest model has shown no problem up to a stored beam current of 1.8 A (1.3 mA/bunch, 6 mm bunch length). Experiences with the comb-type rf shield in these four-year beam tests are reviewed here.
authors.affiliation: High Energy Accelerator Research Organization (KEK), Tsukuba, Ibaraki, Japan.
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Suetsugu
authors.forename: Ken-Ichi
authors.initials: K
authors.lastname: Kanazawa
authors.forename: Kyo
authors.initials: K
authors.lastname: Shibata
authors.forename: Mitsuru
authors.initials: M
authors.lastname: Shirai
authors.forename: Aleksander E
authors.initials: AE
authors.lastname: Bondar
authors.forename: Victor S
authors.initials: VS
authors.lastname: Kuzminykh
authors.forename: Aleksander I
authors.initials: AI
authors.lastname: Gorbovsky
authors.forename: Kurt
authors.initials: K
authors.lastname: Sonderegger
authors.forename: Minoru
authors.initials: M
authors.lastname: Morii
authors.forename: Kakuyu
authors.initials: K
authors.lastname: Kawada