Abstract: A magnet assembly has a generally U-shape, the bight of the U including a permanent magnet which generates a magnetic field whose flux passes through a working volume defined between the arms of the U. The dimensions of the assembly are chosen such that: ##EQU1## where: L.sub.g is the length of the gap between the arms,L.sub.m is the length of the magnet,B.sub.r is the remnant field of the magnet, andB.sub.g is the field in the gap.

Abstract: An apparatus for monitoring characteristics of rock cores using NMR. The apparatus is provided with a clad permanent magnet for generating a magnetic field having a saddle profile. The magnetic field is sufficiently uniform within a working volume to enable an NMR experiment to be performed. Rock cores are conveyed along a path about which the magnet is arranged. The cores pass through the working volume of the magnetic field orthogonally to the saddle profile of the magnetic field. An NMR experiment to monitor oil bearing rock characteristics, such as porosity is carried out on a portion of the rock core within the working volume.

Abstract: An energy storage device comprising an array of electrical coils formed from relatively high temperature superconducting material, the coils being arranged around a common axis and carrying working currents in the same sense.

Abstract: A magnetic field generating assembly used in NMR apparatus includes a primary magnetic field generator for generating a primary magnetic field which is substantially homogeneous in the working region. The primary magnetic field generator is constructed such that an object to be examined can be introduced from outside the assembly into the working region in a direction transverse to the direction of magnetic flux through the working region. Gradient magnetic field coils are provided for imposing one or more magnetic field gradients through the working region. The gradient magnetic field coils are movable relative to the primary magnetic field generator for positioning locally to the position of an object to be examined in the working region.

Abstract: A magnetic field generating assembly having at least two magnetic fields in the same sense. The generators are arranged such that, in use in a working region external to the generators, the resultant magnetic field exhibits a gradient extending in a first direction and at least second order variations in the fields in directions transverse to the first direction within the working region are substantially balanced such that an NMR experiment can be performed on a sample within the working region in accordance with the related method. The magnetic electrical field generators are substantially coaxial electrical coils, wherein the axis extends in the first direction.

Abstract: Magnetic field generating apparatus having a solenoid arranged to generate a steady magnetic field gradient along its axis. The arrangement is such that in use contours of constant field are formed within the solenoid. The contours extend generally radially outwardly from the axis of the solenoid and asymmetrically with respect to the center plane of the solenoid orthogonal to its axis. Regions of substantially homogeneous magnetic field suitable for performing an NMR experiment exist about each contour, the regions having substantially constant thickness along the contours.

Abstract: A magnetic field generating assembly comprises at least two counter-running, nested coils (31-33) positioned between and spaced from opposed pole pieces (42, 43). The pole pieces (42, 43) are mounted to a wall of iron (38-41) surrounding the coils, the walls providing a substantially closed magnetic flux path. The arrangement is such that forces on the coils (31-33) due to magnetic flux in the wall are substantially balanced. The gap between the coils (31-33) and at least one of the pole pieces (42, 43) is sufficient to accommodate a human body. The opposed pole pieces (42, 43) are non-planar so that when working currents flow in the coils (31-33) a magnetic field is generated in working regions (48, 49) situated in the gap between the coils and the pole pieces having homogeneities suitable for performing a nuclear magnetic resonance experiment.

Abstract: A magnetic field generating assembly including self-contained modules formed from relatively high temperature superconducting material. A magnetic flux guide, such as a yoke, is positioned relative to the modules so that magnetic flux generated by the modules is coupled into the flux guide.

Abstract: Magnetic field generating apparatus for example for use in a nuclear magnetic resonance system comprises a first set of coils for generating a first magnetic field in a working volume outside the volume defined by the coils. A separate, second coil is provided spaced from the first set of coils for generating a second magnetic field in the working volume. The arrangement is such that the resultant magnetic field in the working volume is substantially homogeneous. An active shield coil may optionally be provided around the first set of coil.

Abstract: A magnet assembly comprises an array of electrical coils (1-4) positioned side by side in the same sense and arranged such that in use when working currents are supplied to each coil (1-4) a magnetic field of control characteristics is continuously generated in a region (7) spaced from the coils.

Abstract: A magnet assembly, particularly for use in NMR imaging apparatus, comprises a plurality of nested, coaxial coils (2-5). The radius and number of turns of the coils (2-5) are such that when working currents flow through the coils substantially uniform magnetic field is generated in a homogeneous region (16).

Abstract: A magnet assembly, particularly for use in magnetic resonance imaging apparatus, comprises a number of electrical coils (1-6) arranged around and asymmetrically along an axis (8). The relative axial spacing between the coils (1-6) and the fields they generate in use is such that a substantially uniform magnetic field is generated in a homogeneous region (10), the center (11) of the homogeneous region being offset from the geometric center (12) of the assembly.

Abstract: A magnet assembly (1) particularly for use in NMR apparatus comprises a first superconducting coil assembly (A,A'-C,C') for generating a first magnetic field; and a second superconducting coil assembly (D-F) for generating a second magnetic field. The second superconducting coil assembly (D-F) is electrically connected in series with the first superconducting coil assembly (A,A'-C,C'). Each coil assembly (A,A'-C,C'; D-F) generates magnetic fields where corresponding components are of substantially the same order of magnitude whereby a resultant, uniform magnetic field is generated in a working volume (3). The second magnetic field opposes the first magnetic field externally of the magnet assembly (1).

Abstract: A magnet assembly (1) particularly for use in NMR apparatus comprises a first superconducting coil assembly (A,A'-C,C') for generating a first magnetic field; and a second superconducting coil assembly (D-F) for generating a second magnetic field. The second superconducting coil assembly (D-F) is electrically connected in series with the first superconducting coil assembly (A,A'-C,C'). Each coil assembly (A,A'-C,C'; D-F) generates magnetic fields where corresponding components are of substantially the same order of magnitude whereby a resultant, uniform magnetic field is generated in a working volume (3). The second magnetic field opposes the first magnetic field externally of the magnet assembly (1).