Field augmented permanent magnet structures

U.S. Patent Number: 5382936

Abstract: A permanent magnet comprising a shell of magnetic material having a hollow avity and an access port that passes through the shell and communicates with the cavity. The shell is permanently magnetized to produce a magnetic field in the cavity. A magnetic insert is located in the cavity. The insert has a tunnel aligned with the access port and is magnetized in a direction opposite to the direction of the magnetic field. Specifically, a spherical magnetic shell has a concentric cavity in which a spherical magnetic insert is housed. An access port in the form of an axial hole passes through the spherical center of the shell and the insert. The shell ("magic sphere") is magnetized such that it is capable of producing a uniform magnetic field in the cavity. The insert is uniformly magnetized in a direction opposite to that of the cavity field produced by the shell. As such a working field that has a strength greater than that of the cavity field produced by the shell is located in the tunnel. Another embodiment shows a cylindrical shell having an access port in the form of a narrow, gap that passes through the cylindrical shell ("magic ring") and a uniformly magnetized concentric insert. The insert augments the working field that is produced by the shell. An outer, uniformly magnetized shell that houses the structure may be tailored to cancel exterior dipole fields.

Inventors: Leupold; Herbert A. (Eatontown, NJ), Tilak; Anup (Bridgewater, NJ)

Assignee: The United States of America as represented by the Secretary of the Army (Washington, DC)

Application Number: 07/996,281

Issued: 1995-01-17

Expired: 2007-01-17

Classes: 335/306

Field of search: 335/210,296-306 310/90.5 250/396ML 315/5.34,5.35

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