• H. Okuno
  RIKEN Nishina Center, Wako
• A. Adelmann
  PSI, Villigen
• J.J. Yang
  CIAE, Beijing

Since 1997 RIKEN Nishina center has been constructing a next-generation exotic beam facility, RI beam factory (RIBF), based on a powerful heavy ion driver accelerator . Its accelerator complex was successfully commissioned at the end of 2006 and started supplying heavy ion beams in 2007. The four ring cyclotrons (RRC, fRC, IRC and SRC) connected in series accelerate the energy of the heavy ion beams up to 400 MeV/u for the lighter ions such as argon and 345 MeV/u for heavier ions such as uranium. Intensity upgrade plans are under way, including the construction of a new 28 GHz superconducting ECR ion source. The new ECR will take all the succeeding accelerators and beam transport lines to a space charge dominant regime, which should be carefully reconsidered to avoid emittance growth due to space charge forces. Beam dynamics in the low energy cyclotron, RRC was studied by OPAL-cycl a flavor of the OPAL. The simulation results clearly show vortex motions in the isochronous field, resulting in round beam formation in the first 10 turns after the injection point. The possible increase of beam loss at beam extraction will be also discussed in this paper.