Application of Comb-Type RF Shield to Bellows Chambers and Gate Valves

A comb-type RF shield has been applied to bellows chambers and gate valves in a chain of R&D for future high intensity accelerators. The comb-type RF shield has a structure of nested comb teeth, and has higher thermal strength and lower impedance than the conventional finger-type one. Various types of seven bellows chambers have been installed in the KEK B-Factory (KEKB) positron ring since 2003 in series. The temperature of corrugation decreased by a factor of 3 - 6 in most cases. No significant problem has been found in these bellows chamber up to a stored beam current of 1.7 A (1.3 mA/bunch). A circular-type gate valve was also installed in the ring in January, 2005, and promising results were obtained.