CERN, Geneva, Switzerland
TERA, Novara, Italy
INFN/LNS, Catania, Italy
This work presents new superconducting compact cyclotron designs for injection in CABOTO, a linac developed by the TERA Foundation delivering C6+/H2+ beams up to 400 MeV/u for ion beam therapy. Two designs are compared in an industrial perspective under the same design constraints and methods: a synchrocyclotron and an isochronous cyclotron, both at the highest possible magnetic field and with an output energy of 230 MeV/u. This energy allows us to use the cyclotron as a stand-alone accelerator for proton therapy. The synchrocyclotron design features a central magnetic field of 5 T and an axisymmetric pole and a constant field index. The beam is injected axially with a spiral inflector. Resonant extraction allows beam ejection with moderate beam losses. The RF system operates in first harmonic (180° Dee), with modulation provided by a large rotating capacitor. The isochronous cyclotron design features a 3.2 T central magnetic field, four sectors and elliptical pole gaps in the hills and in the valleys. Spiraling is minimized and beam ejection is achieved with a single electrostatic deflector placed inside an empty valley. The two RF cavities operate in fourth harmonic.
