Author: Ohnishi, J.
Paper Title Page
MO1PB01 Acceleration of Intense Heavy Ion Beams in RIBF Cascaded-Cyclotrons 1
  • N. Fukunishi, T. Dantsuka, M. Fujimaki, T. Fujinawa, H. Hasebe, Y. Higurashi, E. Ikezawa, H. Imao, T. Kageyama, O. Kamigaito, M. Kase, M. Kidera, M. Komiyama, H. Kuboki, K. Kumagai, T. Maie, M. Nagase, T. Nakagawa, M. Nakamura, J. Ohnishi, H. Okuno, K. Ozeki, N. Sakamoto, K. Suda, A. Uchiyama, T. Watanabe, Y. Watanabe, K. Yamada, H. Yamasawa
    RIKEN Nishina Center, Wako, Japan
  The RIBF cascaded-cyclotrons have obtained, as of December 2012, uranium ion beams with an intensity of as high as 15 pnA (1 kW of power). This was achieved owing to deployment of a 28 GHz ECRIS, a new injector linac, a gas stripper and a bending-power upgrade of RIKEN fixed-frequency Ring Cyclotron as well as improvement of transmission efficiencies through cyclotrons and stability, etc.   
slides icon Slides MO1PB01 [12.793 MB]  
MOPPT022 Design of New Superconducting Ring Cyclotron for the RIBF 79
  • J. Ohnishi, M. Nakamura, H. Okuno
    RIKEN Nishina Center, Wako, Japan
  At the RIBF, uranium beams are accelerated up to the energy of 345 MeV per nucleon with a RFQ linac, DTL, and four ring cyclotrons (RRC, fRC, IRC, SRC). However, the present beam current of the uranium is 10-15 pnA at the exit of the SRC, still low, because we have to use two charge strippers located upstream and downstream of the fRC to convert the U35+ ions extraced from the 28 GHz ECR ion source to U64+ and U86+, respectively. Accordingly, in order to increase the beam current more than tenfold, we performed the design study of the new superconducting ring cyclotron with the K-value of 2200 which can accelerate the U35+ ions from 11 MeV/u to 48 MeV/u without the first charge stripper. The number of sector magnets is four and the RF frequency is fixed. The maximum magnetic field strength on the beam orbit is 3.2 T, and the superconducting main coils of the dense winding of NbTi and the trim coils of normal-conducting Cu are used. The total weight of the iron yokes is approximately 4800 t. This paper also describes the beam injection and extraction system which includes one superconducting magnetic channel.  
TU1PB04 Status of the RIKEN 28-GHz SC-ECRIS 139
  • Y. Higurashi, M. Kidera, T. Nakagawa, J. Ohnishi, K. Ozeki
    RIKEN Nishina Center, Wako, Japan
  Since we obtained first beam from RIKEN 28GHz SC-ECRIS in 2009, we tried to increase the beam intensity using various methods. Recently, we observed that the use of Al chamber strongly enhanced the beam intensity of highly charged U ion beam. Using this method, we obtained ~180e μA of U35+ and ~230e μA of U33+ at the injected RF power of ~3kW with sputtering method. Advantage of this method is that we can insert the large amount of material into the plasma chamber, therefore, we can produce the beam for long term without break. Actually, we already produced intense U beams for the RIBF experiments longer than month without break. For the long term operation, we observed that the consumption rate of the U metal was ~4mg/h. In this spring, we also produced U beam with high temperature oven and two frequencies injection. In these test experiments, we observed that the beam intensity of highly charged U ions is strongly enhanced. In this contribution, we report the various results of the test experiments for production of highly charged U ion beam. We also report the experience of the long term production of the U ion beam for RIKEN RIBF experiments.  
slides icon Slides TU1PB04 [6.949 MB]