Fixed field alternating gradient ion accelerator for variable energy extraction

A system comprising:

• a charged particle linear accelerator module configured to accelerate a pulse of charged particles as a beam aligned along a first ray;
• and
• a pair of fixed field magnet assemblies configured to turn a moving charged particle 360 degrees within a first plane, wherein the fixed field magnet assemblies are disposed on opposite sides of the linear accelerator along the first ray and the pair of fixed field magnet assemblies is arranged with mirrored symmetry relative to a line perpendicular to the first ray and through a reference point in the first plane not on the first ray, each assembly comprising:
• a pair of magnets for which a strength on the first plane of a magnetic field perpendicular to the first plane varies non-linearly along a radial direction from the reference point;
• wherein the pair of magnets are disposed in the first plane with mirror symmetry about a line parallel to the first ray and through the reference point, and
• a superconducting magnet for which a strength on the first plane of a field perpendicular to the first plane varies along a radial direction from the reference point, the superconducting magnet disposed between the pair of magnets on the first plane.