Abstract: In a nuclear magnetic resonance apparatus the permanent magnetic material of the main magnet is formed by magnetized bars bounded by flat planes which surround a field space with a polygonal cross-section. Fitted around the permanent magnetic material is a return yoke of high-permeability material whose geometry can be matched to the locally prevailing flux. Extra magnetic devices can be fitted to improve the field uniformity in the field space enclosed by the magnetic material.

Abstract: The disclosed nuclear magnetic resonance apparatus has a permanent magnet formed by laterally magnetized bars which are rotatable around their longitudinal axis. If the bars have a circular cross-section, all bars in the magnet system are identical and only the magnetization direction of each bar needs to be matched to the magnetization direction required at the relevant position. If the direction of magnetization in the system satisfies .alpha.=2 .phi. at all times, where .alpha. is the magnetization direction and .phi. the polar coordinate of the relevant bar, efficient use is made of the magnetic material and, in contrast to other magnetization directions, it is possible to work without a return yoke.

Abstract: A nuclear magnetic resonance apparatus comprises an electromagnetic system in which a shield of a magnetic material is arranged about the coil system for the homogeneous magnetic field. By providing the magnetic material, for example soft iron, directly about the coil system, a comparatively compact magnet with an intensified, interference-insensitive homogeneous magnetic field is obtained. Instead of using a closed cylinder, use can alternatively be made of a cylinder which is formed by rods. The latter is notably attractive for shielding at a larger distance, the original field in the coil then being influenced to only a minor extent. A similar shielding can be obtained by means of a Helmholtz coil pair.

Abstract: In a first method, a meander-shaped coil (20,21) is provided on each side of the mask (7) having apertures (9). The coil (21) is oriented perpendicularly relative to the coil (21). If a current flows through the coils (20,21) in the correct direction, a magnetic quadrupole is formed along the circumference of each aperture (9). In a second method, a holder (30,31) with permanent magnetic strips (32) is provided on each side of the mask (7). The strips (32) in the one holder (30) are oriented perpendicularly relative to the strips in the other holder (31).A coil 40 is provided around the holders 30 and 31 with which a decaying magnetic alternating field, is generated which initially drives the material of the mask (7) on both sides of the hysteresis curve into saturation. After the decay of said alternating field a magnetic quadrupole is present along the circumference of each aperture (9).

Abstract: In a first method, a meander-shaped coil (20,21) is provided on each side of the mask (7) having apertures (9). The coil (21) is oriented perpendicularly relative to the coil (21). If a current flows through the coils (20,21) in the correct direction, a magnetic quadrupole is formed along circumference of each aperture (9). In a second method, a holder (30,31) with permanent magnetic strips (32) is provided on each side of the mask (7). The strips (32) in the one holder (30) are oriented perpendicularly relative to the strips in the other holder (31) A coil 40 is provided around the holders 30 and 31 with which a decaying magnetic alternating field is generated which initially drives the material of the mask (7) on both sides of the hysteresis curve into saturation. After the decay of said alternating field, a magnetic quadrupole is present along the circumference of each aperture (9).

Abstract: A hydrogen storage and supply device in which a pressure vessel contains a hydride of the gross formula AB.sub.n H.sub.m, in which A is calcium or one or more of the rare earth metals with or without thorium, zirconium, or hafnium, B is nickel and/or cobalt, with or without iron and/or copper, n has a value between about 3 and 8.5 and m has a value exceeding 0 and up to about 7.

Abstract: A hydride of the gross formula AB.sub.n H.sub.m, in which A is calcium or one or more of the rare earth metals with or without thorium, zirconium, or hafnium, B is nickel and/or cobalt, with or without iron and/or copper, n has a value between about 3 and 8.5 and m has a value up to about 7.

Abstract: An electrochemical energy conversion device, i.e. a galvanic cell using a hydrogen absorbing material to provide either a source of energy, or to absorb hydrogen to avoid overpressure in the cell. This hydrogen absorbing material is a compound of the formula LnM.sub.5 in which Ln represents a lanthanide metal and M is either cobalt or nickel.