Periodic permanent magnet structures

Periodic permanent magnet structures comprise a plurality of paired axially aligned sections of hollow spherical flux sources each of which produces a uniform high-field in its central cavity. Each pair of sections is mounted on opposite sides of a respective plate of permeable material. The magnetic field orientations in the central cavities are axially directed and alternate or reverse in direction from section to section. An axial bore hole drilled through the sections and plates provides a continuous channel or path through which a beam of charged particles will travel.