Design and Magnetic Field Analyses of Spiral Sector Magnet in an FFAG Accelerator for Carbon Cancer Therapy

Abstract

We designed a coil-dominated magnet wound with coated conductors for a spiral sector fixed field alternatinggradient (FFAG) accelerator for carbon cancer therapy. The magnet consisted of deformed pancake coils with negative bends. Coils were arranged like a ladder in order to generate the required radial profile of magnetic field. The positions and the number of the turns of the coils were adjusted iteratively to reduce the magnetic field error. We carried out numerical electromagnetic field analyses of the designed magnet to evaluate the influence of the coated-conductor magnetization (screening or shielding current) on its field quality.