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Kageyama, T.

Paper Title Page
TPPT006 Development of RF Input Coupler with a Coaxial Line TiN-Coated Against Multipactoring 1006
 
  • T. Abe, T. Kageyama, H. Sakai, Y. Takeuchi
    KEK, Ibaraki
 
  In one of the normal-conducting RF cavities used in the KEKB operation, we observed an unexpected rise of the vacuum pressure at certain input-power levels with and without a beam current. From the simulation study, we identify the pressure rises as an effect of the multipactoring discharge in the coaxial line of the input coupler. According to the simulation results, we have decided to make TiN coating on the inner surface of the outer conductor to suppress the multipactoring. In this paper, the status of the development of the TiN-coated input coupler is reported including the recent results of the high-power tests.  
TPPT007 Application of Highly-Pure Copper Lining to Normal-Conducting RF Cavities for an Electron-Positron Super B Factory 1051
 
  • T. Abe, T. Kageyama
    KEK, Ibaraki
  • Z. Kabeya, T. Kawasumi
    MHI, Nagoya
  • T. Nakamura, K. Tsujimoto
    Asahi Kinzoku Co., Ltd., Gifu
  • K. Tajiri
    Churyo Engineering Co., Ltd., Nagoya
 
  We apply a new copper lining with a high purity and a high electric conductivity to normal-conducting RF cavities for an electron-positron super B factory, in which four-times more beam current is required to be stored than in the present KEK B factory (KEKB). The lining is produced first by electroplating in an acid copper sulfate bath without brightener nor other organic additives, where the current is periodically reversed (‘‘PR process''). Its electric conductivity is so high as to be comparable to that of the highest-class oxygen-free copper. Then the copper surface is electropolished to make it smoother. There are two differences between our application and the previous one to the accelerator components for J-Parc. The first one is the lining thickness; our target of 120um is much thinner. The second one is that we have no mechanical polishing on the electroplated surface before electropolishing. In this paper, results of the quantitative estimations of the quality factor on the electroplated pillbox test cavity are reported together with microscale investigations of the copper surfaces.  
TPPT010 HOM Damping of ARES Cavity System for SuperKEKB 1186
 
  • T. Kageyama, T. Abe, H. Sakai, Y. Takeuchi
    KEK, Ibaraki
 
  The ARES cavity scheme is a decisive edge for KEKB to stably accelerate high-current electron and positron beams. The RF structure is a coupled-cavity system where a HOM-damped accelerating cavity is coupled with a large cylindrical energy storage cavity via a coupling cavity between. The HOM-damped structure is designed to be smoothly embedded into the whole coupled-cavity scheme without any structural or electromagnetic incompatibility. Currently, the total HOM power dissipated in the RF absorbers per cavity is about 5 kW according to calorimetric measurements in the KEKB LER with a beam current of 1.6 A. On the other hand, for SuperKEKB aiming at luminosity frontiers over 1035 cm-2 s-1, the total HOM power per cavity is estimated about 100 kW for the LER with the design beam current of 9.4 A. In this article, a new HOM-damped structure of the ARES cavity system designed for the SuperKEKB LER is reported together with the recent activities and future plans for upgrading the HOM absorbers.  
TPPT012 High Power Testing of Input Couplers for SuperKEKB 1294
 
  • H. Sakai, T. Abe, T. Kageyama, Y. Takeuchi
    KEK, Ibaraki
 
  In KEKB, 32 ARES cavities have been successfully operated to stably accelerate high-current electron and positron beams. Currently, each ARES cavity is fed with RF power (frequency = 509 MHz) of about 300 kW through an input coupler, which has a ceramic disk window at the coaxial line section following the doorknob transformer section with a capacitive iris at the rectangular waveguide entrance. For SuperKEKB, which is a challenging project to boost the luminosity frontier beyond 1035 cm-2 s-1, the power capability of the input coupler needs to be upgraded to more than 900 kW, while the design power capability for KEKB is 400 kW. Recently, we have constructed a new test stand in order to simulate the actual operating condition for the input coupler to drive the ARES cavity with the maximum beam loading of 9.4 A expected for the SuperKEKB LER. In this article, the key features of the new test stand are described together with the recent results of high-power tests.  
WPAT009 Status of the RF System for the 6.5 GeV Synchrotron Light Source PF-AR 1168
 
  • S. Sakanaka, K. Ebihara, S. Isagawa, M. Izawa, T. Kageyama, T. Kasuga, H. Nakanishi, M. Ono, H. Sakai, T. Takahashi, K. Umemori, S.I. Yoshimoto
    KEK, Ibaraki
 
  The Photon Factory Advanced Ring (PF-AR) is a 6.5-GeV synchrotron light source at KEK. An rf system comprises two 1.2-MW klystrons, six alternating-periodic-structure (APS) cavities, and other components. It supplies an rf voltage of about 15 MV with a beam current of 60 mA. The system has been working well, except for a trouble (frequent trips with beams) in one of the cavities. We found that the trips were triggered by an irradiation of synchrotron radiation to the cavity wall. In the summer of 2004, we reorganized the rf system, which allows us to install two insertion devices in a part of the rf sections. We replaced the troubled cavity at a time. We report both the operation status and the modification of the rf system.  
WPAT010 RF Dielectric Properties of SiC Ceramics and their Application to Design of HOM Absorbers 1195
 
  • Y. Takeuchi, T. Abe, T. Kageyama, H. Sakai
    KEK, Ibaraki
 
  The KEKB ARES cavity is equipped with two types of HOM absorbers, which are made of different commercial products of the alpha-type SiC ceramics. Their dielectric responses to the RF frequency show the dielectric relaxation properties. Those properties can be clearly explained by the polycrystal structure model with electrically conductive grains and non-conductive grain boundaries. In this article, the RF dielectric properties of the SiC ceramics are discussed together with the application to HOM absorbers.  
RPAE044 Operation and Recent Developments of the Photon Factory Advanced Ring 2845
 
  • T. Miyajima, T. Abe, W.X. Cheng, K. Ebihara, K. Haga, K. Harada, Y. Hori, T. Ieiri, S. Isagawa, T. Kageyama, T. Kasuga, T. Katoh, H. Kawata, M. Kikuchi, Y. Kobayashi, K. Kudo, T. Mitsuhashi, S. Nagahashi, T.T. Nakamura, H. Nakanishi, T. Nogami, T. Obina, Y. Ohsawa, M. Ono, T. Ozaki, H. Sakai, Y. Sakamoto, S. Sakanaka, M. Sato, M. Satoh, T. Shioya, M. Suetake, R. Sugahara, M. Tadano, T. Takahashi, S. Takasaki, Y. Tanimoto, M. Tejima, K. Tsuchiya, T. Uchiyama, A. Ueda, K. Umemori, N. Yamamoto, S. Yamamoto, S.I. Yoshimoto
    KEK, Ibaraki
 
  The Photon Factory Advanced Ring (PF-AR) is a synchrotron light source dedicated to X-ray research. The PF-AR is usually operated at a beam energy of 6.5 GeV, but a 5.0 GeV mode is also available for medical application. In 6.5 GeV mode the typical lifetime of 15 hrs and the beam current of 60 mA with a single-bunch have been archived. Almost full-time single-bunch operation for pulse X-ray characterize the PF-AR. However, single-bunch high-current caused several problems to be solved, including the temperature rise of the some of the vacuum component, a pressure increase in the ring, and a sudden drop in lifetime. In order to avoid these issues the developments of new methods have been continued. In this paper, the status and the recent developments of the PF-AR will be presented. It concerns: the successful operation with two-bunch high-current in 5.0 GeV mode; varying the vertical beam size for the medical application; modulating the RF acceleration phase in order to elongate the length of bunch; stabilizing temperature in the ring tunnel; the study for medium emittance operation with 160 nmrad; moving the RF cavities in order to install a new insertion device; an innovative injection scheme using a pulsed quadrupole magnet.  
TPPP007 Recent Progress at KEKB 1045
 
  • 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
 
  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.