| 摘要 |
A permanent magnet assembly for use in for example magnetic resonance imaging apparatus comprises two spaced apart permanent magnets (1,2) which extend between two plates (3,4) of high permeability material. The permanent magnets and plates define a frame extending around an air gap (5) within which a honmogenous magnetic flux is to be generated. The permanent magnets (1,2) define end surfaces which bear against mating surfaces which bear against mating surfaces of the plates and poles of the permanent magnets of the same polarity face the same plate. The end surfaces of the permanent magnets are non-planar and shaped such that the lengths of inner side surfaces (10,11) of the permanent magnets that form sides of the air gap (5) are less than the length of outer side surfaces (12,13). |
