Abstract: A recondensing zero boiloff superconducting magnet assembly utilizing a cryocooler with a compressible indium gasket positioned between the cryocooler and the recondenser and with the gasket containing a plurality of spaced parallel grid wires with interconnecting web segments of a lesser thickness interconnecting the mid sections of ends of adjacent wires to facilitate compression of the gasket to control improved thermal conductivity while minimizing the pressure and forces on the assembly.

Abstract: Magnetic field homogeneity correction system including coils for a superconducting magnet assembly are wound on the same coil forms as the axially spaced main magnet coils such that they are superimposed radially to simplify the system including design requirements for associated passive shimming and reduce transverse magnetic forces therebetween, and improve magnetic field homogeneity.

Abstract: Vibration and noise isolation for a magnetic resonance imager (MRI) superconducting magnet cryocooler includes a bellows between the cryocooler and its vacuum sleeve in the magnet, a mass suspended along the axis of, but at a distance from, the cryocooler, elastomeric blocks parallel to the axis, and braided copper wires connecting the vacuum sleeve and the heat shields of the MRI. Motion limiters and bellows flexures are provided for dynamic loads which might be encountered during transport of the magnet.

Abstract: A passive non-electric pressure control system for a superconducting magnet cryogen vessel to maintain internal pressure above the outside pressure to avoid cryopumping utilizes a passive thermal conductor extending from the outside atmosphere into the vessel. The selective amount of penetration of the thermal conductor into the cryogen vessel controls the amount of heat transferred to the interior of the vessel and thus controls the internal pressure of the vessel.

Abstract: A helium cooled superconducting magnet assembly with helium gas recondensing apparatus to return liquid helium to the helium supply in the helium vessel in which the recondensing apparatus positioned within the space between the vacuum vessel and surrounding vacuum vessel in thermal contact with a cryocooler within a fixed cryocooler sleeve in the vacuum vessel with the cryocooler positioned to minimize magnetic disturbances to the magnet assembly magnetic field and the recondenser connected through thin corrugated steel tubing to the helium vessel with the tubing sized to provide thermal and vibration isolation of the helium vessel.

Abstract: A cryogen recondensing system magnetic resonance imager superconducting magnet and a cryogen recondensing system with a rare earth displacement material cryocooler and superconductive lead bismuth magnetic sleeve provides superconducting current flow of currents induced by movement of the rare earth displacer which generate opposing magnetic fields to shield the superconducting magnet from the magnetic interference of the cryocooler rare earth displacer. Strips of high conductivity wave-shaped aluminum or sapphire rods may be embedded in the surface of the sleeve to lower the thermal resistance of the superconducting shield to enable it to quickly reach superconducting temperature.

Abstract: A magnetic resonance imaging superconducting magnet including a cryostat, a gradient coil and superconducting gradient shield positioned around the gradient coil with an active resistive shimming member contiguous to the cryostat vessel; and the gradient shield being selectively cooled to superconducting operation after the magnetic shimming fields generated by the shimming member for field homogeneity within the bore of the magnetic resonance imaging magnet are induced onto, and maintained by, the superconducting gradient shield and operation of the resistive shimming member discontinued.

Abstract: A passively shimmed open architecture magnetic resonance imaging magnet utilizing separated superconducting coil assemblies with open space between including means to obtain a uniform magnetic field in the open space by shaped ferromagnetic bands in the bore of the magnets, the shaping including an axial notch and circumferential holes for attaching passive shims.

Abstract: A method of forming a superconducting joint between the Nb.sub.3 Sn layer of a superconducting tape and a superconducting NbTi wire through use of a Pb-Bi bath, joint securing arrangement and mold around the joint.

Abstract: A control system utilizing fuzzy logic adaptive control to control the operation of a wind turbine driven electric power generator to control power generator speed and hence power frequency while maximizing the power output of the power generator. Wind turbulence effects are eliminated and airgap magnetic flux of the power generator is controlled.

Abstract: A helium cooled superconducting magnet assembly including helium gas recondensing apparatus to return liquid helium to the helium supply in the helium vessel includes a recondenser positioned in the helium vessel above the helium supply connected to a cryocooler in a dual-sleeve assembly enabling breaking of thermal joints with thermal isolation from the helium for servicing of the cryocooler during superconducting operation of the magnet assembly, and providing recondensing of helium gas to fall by gravity back to the helium supply.

Abstract: A non-destructive unambiguous method of measuring the presence and level of acid sulfates, particularly ammonium bisulfate in air is disclosed including infrared energy absorbance measurements of particles deposited on the filter through which the air passes.

Abstract: A method to provide large sheets of Nb.sub.3 Sn superconducting material suitable for use as a superconducting gradient shield in a magnetic resonance imaging system magnet by heating an anodized Nb-1 Zr sheet, tin dipping and reacting the sheet, and subsequently quenching the sheet in a purged atmosphere to provide an improved time constant and lowered Jc heating when used in a superconducting magnetic field.

Abstract: Apparatus for forming welded joints on superconducting foils to form long lengths of foil for use in superconducting magnet tapes including fixturing for controlling the accurate positioning of sheared foils and control of the overlap to be welded.

Abstract: A superconducting magnet shield includes a plurality of overlapping NbTi sheets welded together with a plurality of welds extending along elongated parallel slots in the overlap region with the slots extending in the direction of superconducting current flow.

Abstract: A method of forming a crepe paper insulated superconducting magnet coil with fifty percent overlap crepe paper wrapping with the paper wound superconductor subsequently wound into a coil on a coil form pocket using the crepe paper wrap as an insulating and friction reducing component.

Abstract: A magnet including spaced-apart first and second pole pieces with generally opposing first and second pole faces. The first pole face has an axis extending generally towards the second pole face and has a surface region which includes at least two frustoconical surfaces. The frustoconical surfaces are generally coaxially aligned about the axis, and radially-adjacent frustoconical surfaces abut each other. In a second embodiment, points on the surface region located an identical radial distance from the axis are also located a common axial distance along the axis, and a graph of axial distance along the axis versus radial distance from the axis for such points is a curve having a continuous slope with at least two sign reversals. Such contoured pole faces allow for a smoother magnetic field to better reduce axisymmetric magnetic field inhomogeneity.

Abstract: A magnetic resonance imaging magnet including a superconducting gradient shield positioned around the gradient coil and contiguous to the cryogen vessel, with the gradient shield being selectively placed in superconducting operation to shield the magnet coils and structures from the magnetic fields generated by firing the imaging gradient coil positioned within the bore of the magnetic resonance imaging magnet. A plurality of thermally conductive members are compressed between the cryogen vessel and the gradient shield.

Abstract: A positive retraction mechanism for cryogenic thermal joints including deformable interfaces to separate joints which have cold welded utilizing a moveable enclosing sleeve and an actuating mechanism including the force of a compressed bellows to move a retraction flange into engagement with retraction rods which force the thermal joint apart through controlled movement of the retraction flange.

Abstract: An intelligent oxygen injection control system for afterburners which minimizes transient incinerator pollutant emissions while simultaneously minimizing oxygen consumption. A fuzzy logic-based controller utilizes inputs from sensors that measure gas phase pollutant species such as hydrocarbons and carbon monoxide to control oxygen injection and thus minimize pollutant emissions while minimizing oxygen consumption.