Abstract: An orifice pulse tube refrigerator uses flow resistance, compliance, and inertance components connected to a pulse tube for establishing a phase relationship between oscillating pressure and oscillating velocity in the pulse tube. A temperature regulating system heats or cools a working gas in at least one of the flow resistance and inertance components. A temperature control system is connected to the temperature regulating system for controlling the temperature of the working gas in the at least one of the flow resistance and inertance components and maintains a control temperature that is indicative of a desired temporal phase relationship.

Abstract: An orifice pulse tube refrigerator uses flow resistance, compliance, and inertance components connected to a pulse tube for establishing a phase relationship between oscillating pressure and oscillating velocity in the pulse tube. A temperature regulating system heats or cools a working gas in at least one of the flow resistance and inertance components. A temperature control system is connected to the temperature regulating system for controlling the temperature of the working gas in the at least one of the flow resistance and inertance components and maintains a control temperature that is indicative of a desired temporal phase relationship.

Abstract: A stable superconducting switch suitable for use in a conduction-cooled superconducting magnet includes a tape wound in a coil with the tape including an Nb.sub.3 Sn conductor sandwiched between stabilizing layers of copper, bronze or brass and wound in layers, with groups of layers separated by a partial layer of electrically conductive material.

Abstract: A cantilevered trapezoidal-toroidal structure is provided in an active magnetic shielding system for a superconducting magnet to support the bucking magnet coils in spaced relationship to the main magnet coils.

Abstract: A shield is provided for a magnet of the type used in magnetic resonance imaging or spectroscopy to limit the fringe field of a superconducting magnet to specified boundaries when the magnet is generating a magnetic field having a strength required for normal magnet operation. The shield includes a number of steel rectangular plates position around the magnet to form respective sides of a shield, the shield having a cross section in the form of a polygon such as a octrahedron. End caps having the shape of such polygon are joined to the ends of the plates. Structure is provided for supporting the magnet for movement as an integral unit relative to the shield. The supporting structure includes a first set of adjusting mechanisms for moving the magnet vertically and a second set of adjusting mechanisms for moving the magnet laterally, relative to the shield, to move the axis of the magnet into alignment with the shield axis, to avoid magnet quenching and inhomogeneities in the field generated by the magnet.

Abstract: A superconducting switch pack has six switch elements arranged with three in each of two planes. Each switch element is made of a length of cupro-nickel matrix multi-filamentary superconducting wire which is formed into a serpentine shape so as to be bifilar. Primary and back-up heater elements are positioned between the planes of switch elements, and all of the switch elements and heater elements are encapsulated in a solid resin body, with their leads extending outside of the body for connection to electrical circuits. This construction results in a stable superconducting switch pack which is non-inductive, has a high current carrying capability and off resistance. This reduces cryogen boil off of the superconductive circuits connected to the switch pack and makes the switch pack particularly suited for the shim coils of an MR magnet. Each section of the switch pack can also keep magnetic field drifts of the individual superconductive coils to less than 0.

Abstract: A support structure for a superconducting solenoid magnet has a set of five symmetrically and coaxially arranged nonferrous support rings. The central support ring mounts two magnet coils and the other four rings each mount one magnet coil so as to restrain the magnet coils from collapsing toward the center along the magnet bore axis and also to resist radially and circumferentially acting hoop stresses to which the coils are subjected. Tubular struts are symmetrically arranged about the magnet bore axis between adjacent support rings and are seated at their ends in counterbores in the support rings to separate and space apart the support rings. Threaded rods extend through the tubular struts and adjacent support rings to fasten the adjacent rings together.