Patent ID: 8368496

Claim:
A ring magnet assembly comprising a ring magnet body defining an air gap having an upper end and a lower end, a magnetic field extending from one end of said gap upper end and said gap lower end to the other said gap upper end and said gap lower end, an upper face plate disposed at the upper end of said magnet, a lower face plate disposed at a lower end of said magnet, said upper and lower face plates cooperating with said ring magnet body to define a vacuum housing, said face plates being composed of a magnetic material, said face plates having a permeability of about 10,000 to 18,000, said ring magnet assembly being characterized by having a substantially uniform magnetic field extending from one of said gap upper end and said gap lower end to the other said gap upper end and said gap lower end with equidistant field lines, and said ring magnet assembly is structured to provide said substantially uniform magnetic field without requiring the use of externally disposed cladding magnets.