Abstract: This invention relates to linear motor compressors which operate without the use of oil. 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 a superconducting joint which is more commonly referred to as, a pigtail joint, for use in superconducting magnets. Such structures of this type, generally, exhibit total superconducting behavior at temperatures below the transition value of the superconducting joint and have high electrical resistance at temperatures above the transition point of the superconducting joint.

Abstract: This invention relates to refrigerated superconducting eddy current free MR magnets having integrated gradient coils. In particular, the amount of resultant 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 thermal busbar assemblies in a cryostat dual penetration for refrigerated superconductive magnets. Such structures of this type, generally, allow heat to be conducted from the refrigerated superconductive magnet to the refrigeration cold head while isolating the magnet from the vibration created by the cold head.

Abstract: This invention relates to cold head mounting assemblies in a cryostat dual penetration for refrigerated superconductive magnets. Such structures of this type, generally, allow heat to be conducted from the refrigerated superconductive magnet to the refrigeration cold head while isolating the magnet from the vibration created by the cold head.

Abstract: The invention relates to refrigerated superconducting MR magnets having integrated 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 MR image.

Abstract: A method and apparatus for impregnating the superconductors on a superconductor winding with epoxy such that a vacuum/pressure containment vessel, in which the winding is placed, allows epoxy to be introduced into the vessel whereby the epoxy eventually impregnates the superconductors through the application of various evacuating, pressuring and epoxy transporting steps.

Abstract: In an open MRI magnet, the magnet is capable of being rotated such that a patient can be imaged while either lying down or standing up. The open MRI magnet is rotated about a pivot located upon a pedestal.

Abstract: In order to improve image resolution and magnetic field uniformity in a magnetic resonance imaging device, the vibrations and loads produced by the cryocooler are isolated from the superconducting magnet and cryostat. The vibrations and loads are isolated through the use of flexible, laminated copper connectors and rubber mounts.

Abstract: A demountable coil form for fabricating epoxy impregnated superconductive coils having a split ring and a collar clamp secured to the ring on either side of an axially extending opening for adjusting the size of the ring opening. The axially extending opening is widest at its inner diameter and tapers towards the outer diameter of the ring. Cap screws in contact with a wedge and connected to the ring are provided for securing the wedge in the opening in the ring. The wedge has a taper matching the taper of the opening in the ring and is positioned flush with the outer diameter of the ring. Annular side plates are secured to either axial side of the ring, with the side plates extending radially outwardly from the ring. The side plates define slots which create a passageway from the exterior of the side plates to the interior.

Abstract: A superconductive switch for a superconductive magnet is bifilarly wound on a bobbin with niobium-tin tape and laminated with stainless steel foil for structural rigidity is provided. The switch is vacuum pressure epoxy impregnated and cooled by copper bus bars which are heat stationed to a cryocooler which is also used to conduction cool the superconductive magnet. The bus bars are also used to introduce a voltage across the switch and the magnet windings which are connected in series with one another to ramp up the current.

Abstract: Four magnet cartridge axial supports are provided to prevent axial motion between the magnet cartridge and the surrounding vacuum vessel. Each axial support includes two high strength steel rods in parallel. The rods are brazed to a bar on one end which mounts to the magnet cartridge. The other end of the rods is brazed to a threaded stud which is secured by a bolt to a bracket secured to the vacuum vessel.

Abstract: A superconductive foil and a first and second foil of current conducting material. The first and second foil are soldered symmetrically about said superconductive foil forming a superconductive tape. The tape is wound in helical layers forming a coil. Adjacent turns of the tape are electrically insulated from one another. A strip of electrically conductive foil is situated between layers of tape and electrically isolated therefrom. The strip of electrically conductive foil encloses the inner layers of the tape, with the ends of the strip joined together to form an electrically conductive loop. The coil is epoxy resin impregnated.

Abstract: An actively shielded refrigerated superconductive magnet is provided. The magnet includes a generally cylindrical vacuum vessel having an axially extending bore. A plurality of superconductive main coils are positioned in the vacuum vessel concentrically surrounding and spaced away from the bore. A pair of superconductive shield coils having a larger diameter than the superconductive main coils are situated in the vacuum vessel, concentric with the superconductive main coils. The superconductive shield coils are situated at either end of the superconductive main coils. The superconductive shield coils and the superconductive main coils are electrically connected to one another so that the superconductive shield coils and the superconductive main coils are capable of carrying current in opposite circumferential directions. A thermal shield encloses the superconductive main and shield coils, with the thermal shield spaced away from the vacuum vessel and superconductive main and shield coils.

Abstract: A refrigerated superconductive magnet is provided with six magnet cartridge radial struts supporting the magnet cartridge in the vertical and lateral directions. The struts are positioned such that two lateral struts on each end of the magnet cartridge react against the contact force of the cryocooler cold head and support half of the vertical (gravitational) load of the magnet cartridge. Two vertical struts support the other half of the vertical load. The vertical struts pivot to allow the cartridge axial centerline to shrink towards the cryocooler interface during cool down. The strut attachment points have been located near the horizontal midplane in order to minimize the sag of the magnet cartridge due to its own weight.

Abstract: Two pair of thermal shield axial supports are provided. Each support includes a strand of wire brazed on either end into threaded studs. One stud is threaded into a topped hole in the end of the magnet cartridge. The stud on the other end extends through a clearance hole on the end flange of the thermal shield. Belleville spring washers are compressed against the shield by a nut. Prior to cool down, the Belleville washers are compressed. As the shield and magnet cool down, the shield contracts axially with respect to the magnet cartridge, thus relaxing the washer stack compression. The wire tension relaxes from the maximum pretension to a nominal tension at operating temperature.

Abstract: A cylindrical sleeve of thermally conductive material is provided together with two epoxy impregnated superconductive coils. The cylindrical sleeve defines a circumferentially extending rabbet on either end of the sleeve on the inner diameter. The edge of the outer diameter of each coil is secured in one of the rabbets in the sleeve.

Abstract: A magnet cartridge and thermal shield are supported by three concentric nested thin wall tubes from a vacuum vessel. The innermost tube of thermal insulating material is affixed to magnet cartridge at one end and supports the first stage heat station at the other. The intermediate tube of heat conducting material transfers the load from the inner tube to the outer tube which is affixed to the vacuum vessel. The intermediate tube also thermally connects the first stage heat station to the thermal radiation shield. The outer tube also supports the thermal radiation shield. All of the tube joints rely on epoxy-bonded threads to provide good mechanical strength, low motion thermal contact resistance, and no relative motion.

Abstract: A toroidal circumferentially wound superconducting coil is provided for generating a constant magnetic field with a significant radial field component. A room-temperature resistive coil wound circumferentially and connected to launch activating means is coaxial with the superconductive coil. Interaction of the current in the resistive coil with the radial field component of the superconductive coil produces an axial force on the resistive coil and in turn on the launch activating means. The axial force is controllable in magnitude and direction by controlling the magnitude and direction of the current supplied to the resistive coil.

Abstract: A superconductive magnet coolable with a two stage cryocooler is provided. The superconductive magnet includes a cryostat containing a magnet winding, a thermal radiation shield surrounding the magnet winding and spaced away therefrom. The cryostat defines an aperture in which a cryocooler cold head interface receptacle is situated. The interface receptacle has a first and second heat station for connecting in a heat flow relationship with the first and second heat stations of the crycooler, respectively. A precooler has first and second stage heat exchangers connected in a heat flow relationship with the first and second heat stations of said interface, respectively. The interface has an inlet and outlet port for supplying and removing cryogens. Piping means fabricated from heat insulating material connect the first and second heat exchangers in a series flow relationship between the inlet and outlet ports.