Abstract: A superconductive magnet with magnetic shielding has an annularly-cylindrical-shaped housing whose first end wall and outer cylindrical wall are magnetizable (e.g., iron) walls and whose inner cylindrical wall is a non-magnetizable wall. At least one main superconductive coil is positioned within the housing and carries an electric current in a first (e.g., clockwise) direction. An annular first permanent magnet is positioned outside the housing longitudinally proximate the first end wall. The first permanent magnet has a number of equivalent ampere turns and has a magnetic field direction oriented parallel to the axis pointing towards the second end wall so that its magnetic field longitudinally pulls the stray magnetic field of the superconductive coil(s), which leaves the magnet's bore, inward to be captured by the iron first end wall.

Abstract: An open magnet having two magnet assemblies arranged in a spaced-apart, parallel relationship to define a working space therebetween is provided for magnetic resonance imaging. Each assembly has an annular superconductive coil and a ferromagnetic field enhancer encircled by the superconductive coil. The field enhancers are substantially cylindrical ferromagnetic pole pieces which are encircled by a respective one of the superconductive coils. The magnet assemblies are attached to a C-shaped support frame which is rotatively mounted to a pedestal member. The frame can thus be rotated between vertical and horizontal imaging positions. The field enhancers are shaped so as to maximize homogeneity in the imaging volume while keeping their weight and volume to a minimum. The specific shape of the field enhancers is determined with a nonlinear optimization design method.

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: A resistive magnet is provided having a cylindrical radio frequency/gradient coil assembly. A first and second cylindrically shaped main coil is situated coaxially on either side of the radio frequency/gradient coil assembly with the radio frequency/gradient coil assembly and the first and second main coils having the same inside diameter defining a magnet bore. A cylindrical correction assembly coil surrounds the radio frequency/gradient coil assembly. Means for securing the first and second main coil to the cylindrical correction assembly is provided. The radio frequency/gradient assembly provides axial support for the first and second main coil assembly. For additional cylindrical main coils surround the correction coil.

Abstract: A shield for a MR magnet is provided comprising a cylindrical shell of magnetic material surrounding the MR magnet. The cylindrical shell is situated so that its longitudinal axis is coaxial with the magnetic axis of the MR magnet. Two disk shape end caps of magnetic material are secured to either end of the cylindrical shell. The end caps each define a central aperture extending longitudinally through the disk, with the radial extent of each of the apertures sized so that the perturbation of the field in the working volume of the MR magnet due to the cylindrical shell is compensated for.

Abstract: A terminal box for a dynamoelectric machine utilizes a flux shield system wherein a plurality of flux shields are interposed between the wall of the terminal box and a high voltage bushing. Cooling fluid is passed through the flux shield system to maintain all parts at a safe, low temperature. In one embodiment of the invention, a first inner flux shield member of high electrical conductivity and low magnetic permeability is spaced from but surrounding the bushing. A second outer flux shield member of low electrical conductivity and high magnetic permeability is spaced between the first shield member and the terminal box wall. Passages and openings are provided to allow cooling fluid to circulate over the respective shield members and the wall of the terminal box without providing a path for transmission of flux from the area surrounding the bushing to the terminal box wall.