Magnetic field design of a Superconducting magnet for a FFAG accelerator

A superconducting magnet for a Fixed Field Alternating Gradient (FFAG) accelerator is proposed. The static magnetic field is required to be proportional to the k-th power of the orbit radius where k is the geometrical field index of the accelerator. The left/right asymmetric coil with elliptical aperture is introduced to maximize the horizontal aperture with a compact magnet design. The 3D coil configuration is designed to meet the requirement in terms of integral magnetic field. The 3D magnetic field is evaluated and the field integral along the beam trajectory satisfies the beam optics requirement of the FFAG accelerator.