A compact superconducting cyclotron for the production of high intensity protons

This paper reviews a study of a compact superconducting cyclotron to accelerate 200 microamps of protons to 250 MeV. The basic cyclotron structure is the same as that developed in a previous study of a 250 MeV cancer therapy cyclotron, the chief difference in the study reported here being much higher beam current (x10,000) than in the therapy cyclotron to meet desired specifications for the `Driver´ accelerator of an ISOL type radioactive beam facility. The increase in current is far below (x1/50) the axial space charge limit of the proposed cyclotron, but longitudinal space charge requires changing the extraction system from a single turn to a multi-turn system thereby increasing beam losses. Leading design uncertainties, namely the overall efficiency of the multi-turn extraction system and the distribution of radioactivity generated by lost beam are addressed herein; results indicate reasonable residual activity in the cyclotron from the perspective of customary `hands-on´ maintenance operations