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Takeuchi, Y.

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.  
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.  
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.  
RPPE002 Installation and Radiation Maintenance Scenario for J-PARC 50 GeV Synchrotron 835
 
  • M. Yoshioka, H. Kobayashi, T. Oogoe, Y. Takeuchi, Y. Watanabe
    KEK, Ibaraki
  • Y. Kuniyasu
    MELCO SC, Tsukuba
  • H. Oki, Y. Takiyama
    ,
 
  Funding: Ministry of Education, Culture, Science and Technology, Japan

J-PARC comprises a 400 MeV linac (181 MeV at the first stage), a 3 GeV rapid-cycling synchrotron and a 50 GeV synchrotron (Main Ring), which will provide high power proton beam to the material and life science facility, the neutrino facility and the nuclear and particle physics experimental hall. The installation of the accelerator components for the Main Ring will be started on mid. 2005 and the beam commissioning is scheduled in end of 2007. This paper describes the installation scenario of the accelerator components into the main ring tunnel and the development of radiation maintenance scenario for the beam injection and ejection systems.

 
ROPA003 Present Status of the J-PARC Control System 302
 
  • T. Katoh, K.  Furukawa, N. Kamikubota, H. Nakagawa, J.-I. Odagiri, G.S. Shen, Y. Takeuchi, N. Yamamoto, M. Yoshii
    KEK, Ibaraki
  • H. Sakaki, H. Sako, H. Takahashi, F. Tamura, H. Yoshikawa
    JAERI, Ibaraki-ken
  
  Construction of the J-PARC control system is in progress and the present status is reported. The control system is based on EPICS tool-kit used in KEKB and other accelerator control systems at KEK. The control hardware and network system for Linac and RCS(Rapid Cycling Synchrotron) have been installed and software is under development now. The operation of Linac is expected in next year. The test of the first part of the accelerator complex; e.g. ion source, RFQ and the first DTL(20 MeV) were done at KEK site. Development of various software such as device drivers for the new equipment, device support routines, and some application programs for operators were also developed.