The Magnetic Field Design of HITFiL Cyclotron

A new Project named HITFiL (Heavy Ion Tumors Therapy Facility in Lanzhou) is being constructed. Its initial injector is a compact cyclotron, which provides a 7 Mev/10 uA carbon beam for the synchrotron. This paper introduces an effective method to design the isochronous magnetic field of the cyclotron. Using a 3D finite element code, an iterative shimming process has been accomplished successfully. The results show that the isochronous deviations between calculated values and theory are smaller than 5 Gauss at most radii and therefore fulfill the requirements. In addition, the magnetic design of the extraction magnets and their interaction with the main field will be presented in this paper.