Patent ID: 6970061

Claim:
A magnet structure, comprising: a frame supporting first and second opposing permanent magnet assemblies; wherein the frame includes a base, first and second extensions connected to the base and to the respective first and second opposing permanent magnet assemblies, and first and second support structures supporting the respective first and second opposing permanent magnet assemblies with respect to the base; and wherein the first and second opposing permanent magnet assemblies each include an enclosure having an open end, a pole, disposed on the enclosure, having a pole face, and arranged such that the pole face opposes the pole face of the other permanent magnet assembly, a magnetic mass disposed within the enclosure, and a cover over the open end of the enclosure; wherein the magnetic mass is a plurality of discrete magnetic elements made from a first magnetic material, the discrete magnetic elements are bricks made from a first magnetic material, the bricks include main bricks oriented so as to direct a main magnetic field in a first direction, and bucking bricks oriented to direct a blocking magnetic field in a second direction, the main bricks are disposed behind the respective pole face and direct the main magnetic field generally toward the respective pole face, and the bucking bricks include first bucking bricks and second bucking bricks, wherein the first bucking bricks are disposed at a first side of an outside periphery of the respective pole face and direct the blocking magnetic field toward a first center line of the respective pole face, and the second bucking bricks are disposed at a second side of the outside periphery of the respective pole face, adjacent the first side of the outside periphery of the respective pole face, and direct the blocking magnetic field toward a second center line of the respective pole face.