Patent ID: 6411187
Filing Date: 2002-06-25
Classification: G01R,H01F

Abstract:
An open magnetic apparatus for producing a predetermined volume of substantially uniform magnetic field directed parallel to an axis of symmetry of said volume, the apparatus comprising:a first electromagnet assembly disposed at a first position along said axis, said first electromagnet assembly includes at least a first electromagnet coil, said at least first electromagnet coil is radially symmetric with respect to said axis; a second electromagnet assembly disposed at a second position spaced apart from said first position of said first electromagnet assembly along said axis, said second electromagnet assembly includes at least a second electromagnet coil, said at least second electromagnet coil is radially symmetric with respect to said axis, said at least first electromagnet coil and said at least second electromagnet coil are substantially equidistant from the center of said is volume, said first electromagnet assembly and said second electromagnet assembly are configured for generating a first magnetic field within said volume; a first permanent magnet assembly positioned at a third position disposed between said first position and said second position along said axis, said first permanent magnet assembly has an inner surface facing said volume and an outer surface facing said first electromagnet assembly, said first permanent magnet assembly includes at least two coaxial permanent magnets, said at least two permanent magnets are radially symmetric with respect to said axis; and a second permanent magnet assembly opposed to said first permanent magnet assembly, said second permanent magnet assembly is positioned at a fourth position spaced apart from said third position along said axis, said second permanent magnet assembly has an inner surface facing said volume and an outer surface facing said second electromagnet assembly, said second permanent magnet assembly includes at least two coaxial permanent magnets, said at least two permanent magnets of said second permanent magnet assembly are radially symmetric with respect to said axis, said inner surface of said first permanent magnet assembly and said inner surface of said second permanent magnet assembly define an open region therebetween, said volume is disposed within said open region, said third position of said first permanent magnet assembly and said fourth position of second permanent magnet assembly are substantially equidistant from the center of said volume along said axis, said first permanent magnet assembly and said second permanent magnet assembly are configured for generating a second magnetic field superimposed on said first magnetic field to provide said substantially uniform magnetic field within said volume.