Abstract: A superconductive magnet subassembly has a single unbroken length of superconductive conductor which has a mid portion wound so as to define at least one superconductive magnetic coil and which has two end portions superconductively joined together by a superconductive joint. A superconductive switch is at least partially defined by the two end portions and by a heater for controllably heating the two end portions.

Abstract: A superconducting magnet including a superconducting coil assembly having a magnet cartridge, a cryocooler coldhead having a cold stage in thermal contact with the magnet cartridge, and a thermal buffer assembly. The thermal buffer assembly includes an inlet tube and an outlet tube each having an end connected to a helium pressure container which is placed in thermal contact with the magnet cartridge. A first gas pressure regulator on the inlet tube supplies helium gas and a second gas pressure regulator on the outlet tube vents helium gas so as to maintain a generally constant pressure for the helium gas within the helium pressure container. The high specific heat per unit volume of the pressurized gaseous helium acts as a thermal buffer to extend the time the magnet can operate superconductively without the cryocooler before quenching, such as during an electric power outage.

Abstract: An open magnetic resonance imaging (MRI) magnet having first and second spaced-apart superconductive coil assemblies each including a toroidal-shaped coil housing containing a superconductive main coil and a superconductive bucking coil. The bucking coil is spaced radially inward and radially apart from the main coil. The bucking coil carries an electric current equal in amperage, and opposite in direction, to the main coil. The bucking coils overcome the gross magnetic field distortions in the imaging volume of the main coils (created by the open space between the magnet's superconductive coil assemblies) to produce a magnetic field of high uniformity within the imaging volume.

Abstract: A superconducting magnet lead assembly for a cryocooler-cooled superconducting magnet having a design current of between generally 50 and 250 amperes. A DBCO (Dysprosium Barium Copper Oxide), YBCO (Yttrium Barium Copper Oxide), or BSCCO (Bismuth Strontium Calcium Copper Oxide) superconducting lead has its ends flexibly, dielectrically, and thermally connected, one end to the generally 30 to 50 Kelvin first stage and the other end to the generally 8 to 30 Kelvin second stage of the cryocooler coldhead. The superconducting lead has a generally constant cross-sectional area along its length. The design current, the lead's length, and the lead's cross-sectional area are chosen such that the design current times the lead's length divided by the lead's cross-sectional area is between generally 720 and 880 amperes per centimeter for a DBCO or YBCO lead and is between generally 180 and 220 amperes per centimeter for a BSCCO lead. The superconducting lead will not itself precipitate a magnet quench (i.e.

Abstract: This invention relates to a field mapping fixture for mapping the magnetic fields of a superconducting magnet. Such structures of this type, generally, are capable of measuring the magnetic fields of a relatively small imaging volume.

Abstract: A magnetic resonance imaging (MRI) magnet having an annularly cylindrical-shaped vacuum enclosure with a longitudinal axis, first and second longitudinal ends, a first larger diameter bore extending from the first towards the second longitudinal end, and a second smaller diameter bore extending from the second longitudinal end to the first bore. First and second superconductive coils are placed in the vacuum enclosure with the first coil generally circumferentially surrounding the first bore and the second coil circumferentially surrounding the second bore, wherein the radial distance of the radially innermost portion of the second coil from the axis is smaller than the radius of the first bore. The second longitudinal end of the vacuum enclosure fits on a patient's shoulders with the patient's head passing through the second bore and extending into the first bore for MRI brain imaging.

Abstract: An open magnetic resonance imaging (MRI) magnet having first and second spaced-apart superconductive coil assemblies connected by spaced-apart structural posts each having a first end portion attached to the coil form of the first coil assembly and a second end portion attached to the coil form of the second coil assembly. Each toroidal shaped coil form has radially spaced-apart inner and outer generally cylindrical shells and has longitudinally spaced-apart inner and outer annular plates each attached to the inner and outer cylindrical shells. A superconductive coil surrounds, and is attached to, the outer surface of the outer cylindrical shell.

Abstract: A magnetic resonance imaging magnet includes a cryocooler penetration assembly and a superconducting coil assembly. The cryocooler penetration assembly has a thermal station within a thermal box within a vacuum vessel. The superconducting coil assembly has a magnet cartridge within a thermal shield within a vacuum enclosure. A flexible bellows hermetically connects the vacuum vessel and the vacuum enclosure. A first rigid thermal busbar is rigidly attached to the thermal shield, and a first flexible thermal busbar thermally connects the thermal box and the first rigid thermal busbar. A second rigid thermal busbar is rigidly attached to the magnet cartridge, and a second flexible thermal busbar thermally connects the second rigid thermal busbar and the thermal station.

Abstract: This invention relates to a pole face design for superconducting magnets of the type that are C-shaped. Such structures of this type, generally, employ pole faces which homogenize the magnet field within the imaging volume.

Abstract: A cold head sleeve and superconducting lead assembly including a cryocooler and a tube operatively connected to the cryocooler. A first and second heat station are operatively connected to the cryocooler with a magnet cartridge operatively connected to the first heat station and a thermal shield operatively connected to the second heat station. A thermal connector is operatively connected to the magnet cartridge and thermal shield, and a superconducting lead is operatively connected to the thermal connector.

Abstract: This invention relates to linear motor compressors which operate without the use of oil and a gas bearing while providing a flexible suspension for such a compressor. Such structures of this type, generally, provide a highly reliable oil-free compressor for use with cryogenic refrigeration equipment so as to attain unattended, continuous operation without maintenance over extended periods of time.

Abstract: This invention relates to an apparatus and method for providing passive shimming for a superconducting magnet of the type that has a relatively small imaging volume. Such structures of this type, generally, provide the proper amount of passive shimming for a relatively small imaging volume.

Abstract: An open magnet having a frustoconical shaped inner bore is provided for MR imaging. The magnet has a plurality of axisymmetric superconducting coils of differing diameters which are disposed along an axis in order of successively increasing diameters so as to define the frustoconical shape. This shape permits a patient access opening which is much larger than that in conventional cylindrical magnets. The overall length is much less than the length of conventional systems. The combination of wide opening and short length facilitates patient access and presents a feeling of openness. Furthermore, the device can be tilted with respect to horizontal to increase the openness.

Abstract: This invention relates to a superconducting magnet of the type that has a relatively small imaging volume. Such structures of this type, generally, allow the operator to image human limbs without the use of a larger, more costly superconducting magnet.

Abstract: This invention relates to current leads for a superconducting magnet system of the type that are constructed of two-stages. Such structures of this type, generally, operate from ambient temperature to the temperature at the thermal shield and from the temperature of the thermal shield to that of the magnet such that ohmic losses are reduced.

Abstract: This invention relates to a cryogenless superconducting magnet system of the type that is attached to a utility grid at end-user site and is used to store electrical energy until such time that an electrical disruption occurs in the grid. Structures of this type, generally, allow the stored electrical energy to be released in such a manner that the disruption in the utility grid is negated before it reaches critical loads.

Abstract: Composite superconducting windings of the type that have superconductor wires wound with glass cloth, an array of axial insulated copper wires, copper foil straps of expanded metal or perforated foil which are positioned between winding layers to reinforce the composite winding and enhance the thermal conductivity of the winding, and an overwrap of high strength stainless steel wires to provide additional rigidity to the composite winding. Structures of this type, generally, form a self-supported, structurally robust composite winding and support structure that is capable of withstanding the hoop and axial stresses that result from the electromagnetic loads created by the superconductor.

Abstract: This invention relates to refrigerated superconducting MR magnets having integrated cryogenic gradient coils. In particular, the amount of eddy currents produced by the magnet are substantially reduced while reducing the size and weight, and, therefore, the cost of the superconducting magnet required to produce an acceptable MR image.

Abstract: This invention relates to balanced linear motor compressors which operate without the use of oil and externally tuned resonant balancers. Such structures of this type, generally, provide a highly reliable oil-free compressor which is internally balanced for use with cryogenic refrigeration equipment so as to attain unattended, continuous operation without maintenance over extended periods of time.

Abstract: This invention relates to high-Tc superconducting lead assemblies in a cryostat dual penetration for refrigerated superconductive magnets. Such structures of this type, generally, provide electrically isolated current paths with minimal heat leak between the 10K thermal station and the 50K thermal station while allowing for differential thermal contraction in the assembly, thus avoiding undesirable stresses in the leads.