MAGNETIC STRUCTURE HAVING A MIRROR

摘要

A magnetic structure defining a cavity (20) includes a first member (30) of high permeability material having a flat surface defining a first wall of the cavity, and a member of permanent magnet material (10) spaced from the flat surface and producing a uniform field in the cavity. The permanent magnetic material member may have two or more layers, with the layers outward of the cavity being of a material having a remanence that is no greater than the adjacent inner layers.