• H. Sato, t.s. Shintomi
  KEK, Ibaraki
• T. Ise, Y. Miura
  Osaka University, Graduate School of Engineering, Osaka
• S. Nomura, R. Shimada
  RLNR, Tokyo

Magnets of the synchrotron accelerator which extracts the accelerated beams are excited by pulse operation power supply, and then the load fluctuation should be a severe problem. An energy storage system, such as SMES, fly-wheel generator so far, will be required for compensating the pulse electric power, and reducing the disturbances of the connected power line. The system is also expected to protect the instantaneous voltage drop and contributes the reliability of the storage ring. Present status of R & D and the features for the energy storage systems are discussed. The application of the energy storage systems to synchrotrons for the medical use is described. The compensation of the typical pulse electric power of the synchrotron for the cancer therapy is studied.