Superconducting Coil System R&D for a 230-MeV Superconducting Cyclotron

Started in January 2015, a 230-MeV superconducting cyclotron is under construction in the China Institute of Atomic Energy for proton therapy. A compact main magnet design with warm iron yokes and a superconducting coil system is adopted to reduce the size, construction, and operation cost of the cyclotron. In this paper, the field calculations of the main magnet are briefly described; then, the R&D of the superconducting coil system are outlined in detail, including the cryogenics design of the system, the forces, and stress analysis of the superconducting coil and support links, the power supply and quench protection design. Some preliminary test results are also presented.