Houston Advanced Research Center

Hewlett-packard Company

Sergio Pissanetzky

Peter M McIntyre

John D Larson

F Russell Huson

An apparatus and method for bending magnetic flux in a magnetic circuit are disclosed. A means for conducting a substantially planar electric current is placed in the path of the flux of a magnetic circuit. Current is then caused to flow in the conducting means, causing the magnetic flux in the magnetic circuit to deviate from its original path. A preferred embodiment of the invention is described wherein a series of coils are used to form both the planar conducting means and a partial flux conduit for coupling the flux bending apparatus to the magnetic circuit. Specific applications of the invention are disclosed in relation to magnets for use in magnetic resonance imaging applications, and magnets for use in dual dipole particle accelerator applications. Additional applications of the invention are described in relation to creating modular components for magnetic flux piping systems, such components including devices for splitting and recombining magnetic flux, concentrating and expanding magnetic flux, and switching magnetic flux to two or more different paths. Also disclosed are applications of the invention to create magnetic circuits wherein the flux pipes have a size on the order of microns. Specifically, a data storage device is disclosed containing micron-sized flux pipes and flux switching devices fabricated on a substrate and integrated with other circuitry.

Magnetic flux bending devices

Structured coil electromagnets for magnetic resonance imaging

A compact, open geometry U-shaped magnet formed by parallel iron slabs and a flux return is activated by a coil which surrounds the flux return. The inner surfaces of the iron slabs and an outer surface of the coil are substantially contiguous. The field homogeneity within the compact, open geometry U-shaped magnet is improved by controlling the reluctance of a secondary flux flow circuit extending away from the pair of parallel iron slabs. The geometry of the compact, open geometry U-shaped magnet also provides for utilization of an automatic active shimming system.

Compact, open geometry U-shaped magnet for magnetic resonance imaging

Superconducting electromagnets suitable for use in the NMR tomography of human organs, and a method of making the same, are disclosed. Each of the disclosed electromagnets are constructed according to a structured coils methodology, where the desired field at locations within the volume of interest and, optionally, outside of the location of the coils is selected; the current magnitude and polarity for a plurality of coil elements locations are then optimized, by way of a computer program, to provide the desired field magnitude at the locations. The magnet construction results in a plurality of coils of varying current polarity, and of irregular shape and size, optimized to provide the uniform field. Magnets may be constructed according to the present invention which provide suitably highly uniform and high magnitude DC magnetic fields at volumes of interest which may be within or outside of the magnet bore, enabling the MRI of human organs without requiring whole body insertion of the patient into the magnet bore.

Structured coil electromagnets for magnetic resonance imaging and method

A superconducting magnet suitable for use in magnetic resonance imaging applications is disclosed. A plurality of driving coils are located around a cylindrical bore, for generating an axial magnetic field therein. At the ends of the magnet, within the same cryostat as the driving coils, first and second shielding coils are located, each carrying a current of opposite polarity relative to the driving coils. The location, size, and current in the coils are determined by a methodology in which the error between the desired field and the simulated field is minimized at target locations within the bore and outside of the bore. A flux return is disposed in the gap between the first and second shielding coils, so that the shielding coils inject return magnetic flux into the flux return. The flux return may be of iron, or may consist of a superconducting coil. The resulting magnet has relatively low superconductor cost as well as relatively low weight, due to the efficient use of both superconductor and iron.

Ultrashort cylindrical shielded electromagnet for magnetic resonance

A C-shaped superconducting magnet for use in magnetic resonance imaging (MRI) equipment is disclosed. The magnet includes flux concentrators on opposing sides of the gap, for generating a vertical field therein; the flux concentrators include a plurality of coils, for carrying current in opposing directions, so as to generate an inwardly directed field to compensate for the gap. Injection correctors, each consisting of a horizontal coil, are disposed adjacent the flux concentrators. A flux return body, for example a superconducting solenoid or an iron yoke, provides a return path on the opposite side of the magnet from the gap. Flux deflectors guide return flux in a curved path from the flux return body to the injection correctors. The flux deflectors are constructed to include a superconducting coil which is wound about varying chords (or the full diameter) thereof, so that the induced flux is greater nearer the outside of the flux deflector, compensating for the tendency of the flux to crowd along the inner portion of the curved path. The return flux is thus provided to the injection correctors with sufficient uniformity to be corrected thereby.

Growing community of inventors

The Woodlands, TX, United States of America

Sergio Pissanetzky