Author: Tomizawa, M.
Paper Title Page
MOPPD051 Performance of Resonant Slow Extraction from J-PARC Main Ring 481
  • M. Tomizawa, Y. Arakaki, T. Kimura, S. Murasugi, R. Muto, H. Nakagawa, K. Okamura, H. Sato, Y. Shirakabe, T. Toyama, E. Yanaoka, M. Yoshii
    KEK, Ibaraki, Japan
  • D. Horikawa
    Sokendai, Ibaraki, Japan
  • K. Mochiki
    Tokyo City University, Tokyo, Japan
  • A. Schnase
    JAEA/J-PARC, Tokai-mura, Japan
  Proton beam accelerated by the J-PARC main ring (MR) with an imaginary transition lattice is slowly extracted by a third integer resonant extraction scheme and delivered to the hadron experimental hall. One of the critical issues in the slow extraction from a high intensity proton synchrotron is the inevitable beam loss caused by the extraction process at septum devices. A design with low beam loss (high extraction efficiency) is required to reduce machine damage and radiation exposure during hands-on maintenance. We have designed the slow extraction scheme to obtain high extraction efficiency for the MR lattice. The scheme has a large step size and a small angular spread enabling a hit rate of the beam on the developed thin septum device. Since the first 30 GeV proton beam was successfully delivered to the experimental hall in January 2009, an extremely high extraction efficiency of 99.5% has been achieved by an intensive beam tuning. In this paper, we report details of such performance. We will also describe some schemes to improve the serious spiky spill time structure due to large current ripples from the power supplies for the bending and quadrupole magnets.  
MOPPD052 Study of Electrostatic Septum by Low-Z Material for High Intensity Proton Beam 484
  • D. Horikawa
    Sokendai, Ibaraki, Japan
  • Y. Arakaki, K. Okamura, Y. Shirakabe, M. Tomizawa
    KEK, Ibaraki, Japan
  • I. Sakai
    University of Fukui, Faculty of Engineering, Fukui, Japan
  • T. Shimogawa
    Saga University, Faculty of Science and Engineering, Saga, Japan
  In a high-intensity proton accelerator, the beam loss at the time of late beam extraction causes radioactivation of apparatus. It takes out and is a problem serious to that of upper about beam power. Its attention was paid to electric septum (ESS) of the equipment used for beam extraction for problem solving. The septum section of ESS which beam hits directly is usually used for tungsten. Therefore, it is low atomic number material to the septum section. Development of the new model ESS using the textile material carbon fiber of a certain carbon (CF) was started. Is it a problem in CF at processability? Is it using for the septum section of ESS for a certain reason? Difficult it was. Therefore, it succeeded in obtaining required form and intensity by developing the twisting thread technology of CF. Moreover, the tension strength test of CFwire and the pyrogenicity test by electric current were done. Is it the tension intensity and heat durability which exceed the existing tungsten wire? It was confirmed. In addition to the ESS development technique using these new materials, and a result, a future measure is reported.