| Paper |
Title |
Page |
| TPPP007 |
Recent Progress at KEKB
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1045 |
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- Y. Funakoshi, K. Akai, K. Ebihara, K. Egawa, A. Enomoto, J.W. Flanagan, H. Fukuma, K. Furukawa, T. Furuya, J. Haba, S. Hiramatsu, T. Ieiri, N. Iida, H. Ikeda, T. Kageyama, S. Kamada, T. Kamitani, S. Kato, M. Kikuchi, E. Kikutani, H. Koiso, M. Masuzawa, T. Mimashi, A. Morita, T.T. Nakamura, H. Nakayama, Y. Ogawa, K. Ohmi, Y. Ohnishi, N. Ohuchi, K. Oide, M. Ono, M. Shimada, S. Stanic, M. Suetake, Y. Suetsugu, T. Sugimura, T. Suwada, M. Tawada, M. Tejima, M. Tobiyama, N. Tokuda, S. Uehara, S. Uno, N. Yamamoto, Y. Yamamoto, Y. Yano, K. Yokoyama, M. Yoshida, M. Yoshida, S.I. Yoshimoto
KEK, Ibaraki
- F. Zimmermann
CERN, Geneva
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We summarize the machine operation of KEKB during past one year. Progress for this period, causes of present performance limitations and future prospects are described.
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| RPPE052 |
Application of Comb-Type RF-Shield to Bellows Chambers and Gate Valves
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3203 |
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- Y. Suetsugu, K.-I. Kanazawa, N. Ohuchi, K. Shibata, M. Shirai
KEK, Ibaraki
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A comb-type RF-shield, which was recently proposed for high current accelerators, was experimentally applied to bellows chambers and gate valves. The comb-type RF-shield has a structure of nested comb teeth, and has higher thermal strength and lower impedance than usual finger-type RF shields. The shield is suitable for future high intensity accelerators, such as particle factories aiming a luminosity of 1·1035 - 36 /cm2 /s. Seven bellows chambers with a circular or a racetrack cross section had been installed in the KEKB (KEK B-factory) positron ring since 2003 in series. Some bellows chambers are forced to bend up to 20 mrad during the beam operation. No significant problem had been found with a stored beam current up to 1.6 A (1.25 mA/bunch). On the other hand, a circular-type gate valve with the comb-type RF shield will be installed in the ring in January, 2005. Structures, properties and results of the beam test of the bellows chamber and the gate valve are discussed.
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| RPPE053 |
R&D Status of Vacuum Components for the Upgrade of KEKB
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3256 |
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- Y. Suetsugu, H. Hisamatsu, K.-I. Kanazawa, N. Ohuchi, K. Shibata, M. Shirai
KEK, Ibaraki
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An upgrade plan of the KEK B-factory (KEKB), Super KEKB, aiming a luminosity over 1·1035 /cm2 /s has been discussed in KEK. To achieve the high luminosity, the stored beam currents are 4.2 - 9.4 A and the bunch length is 3 mm. In designing the vacuum system of the Super KEKB, therefore, the main issues are how to manage the resultant highly intense synchrotron radiation (SR) power, and how to reduce the beam impedance. The R&Ds for basic vacuum components, such as a beam duct, a bellows chamber, a connection flange, a collimator, a high-capacity pump and so on, are now undergoing to deal with the problems. For examples, a copper beam duct with an antechamber was manufactured to reduce the power density of SR, and to suppress the electrons around the beam for the positron ring. The test chamber was installed in the positron ring of KEKB and tested with a beam. Bellows chambers with a newly developed RF-shield were also installed in the ring and the property was investigated. A special connection flange with little step or gap inside was developed and examined in a test bench. The designs of these components and the results of tests are presented and discussed.
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| FPAP007 |
Measurement of the Electron Cloud Density Around the Beam
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1054 |
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- K.-I. Kanazawa, H. Fukuma, H. Hisamatsu, Y. Suetsugu
KEK, Ibaraki
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Under the present operating condition of KEKB LER, most high energy electrons in the electron cloud that hit the chamber wall are produced near the circulating bunch by the single kick. By separating the high energy component of the electron current monitored at a pump port of a vacuum chamber, the density of the electron cloud near the beam is estimated. The estimated density is close to the order of magnitude expected from simulation. At present there still remains an ambiguity that comes from the detector efficiency in the measurement and the assumed secondary electron yield in the simulation.
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