Operational Experience and Upgrade Plans of the RIBF Accelerator Complex

The Radioactive Isotope Beam Factory (RIBF) is the cyclotron based accelerator facility for nuclear science, completed in the end of 2006. Now RIBF can provide the most intense RI beams. Continuous efforts since the first beam has increased the beam intensity and made stable operation. In 2016, 49.8 pnA (3×10¹¹/sec) of uranium ion beam could be extracted from the final accelerator SRC with energy of 345 MeV/u. An intensity upgrade program has been proposed to increase the intensity of uranium ion by more than twenty. The program includes two subjects. First, space charge limit of the beam intensity in the low energy ring cyclotron (RRC) should be increased by replacing the existing resonators with the new one to get higher accelerating voltage. The second is skip of the first stripper, requiring a new ring cyclotron (FRC) just after the first stripper to increase the maximum magnetic rigidity so as to accept low charge state. This presentation show a conceptual design of the new cyclotron with some issues to realize the intensity upgrade.