Development of Sector Magnets for the RIKEN Superconducting Ring Cyclotron. Superconducting Coils and Their Cryogenic Stabilization.

Superconducting sector magnets are to be the main components of the superconducting ring cyclotron for the RIKEN RI beam factory. The sector magnet has superconducting main and trim coils. A cryogenic stabilization method is applied to both coils in order to make them quench-free. Both superconducting coils and their wires, design of stabilization, quench simulation, and measurement of the stabilized currents using small test coils are described.