摘要:
Permanent magnets for producing an intense field. A main magnetic circuit comprises two magnets (1, 1'), two pole pieces (2, 2') and a yoke (3). Two additional magnets (6, 6') of opposite magnetization reinforce the field in the air gap (5) while extending into the latter between edges (25, 25', 26, 26', 27, 27', 28, 28') of magnets (1, 1') and pole pieces (2, 2'). Application to imaging by magnetic resonance (tomography).
摘要:
A system of coils is disclosed for the production of imaging by nuclear magnetic resonance of gradients Gx and Gy. The system of coils is disposed on the outer surface of a straight cylinder of revolution of axis Oz and radius R. The coils include four patterns of conductor wires which are pairwise symmetrical with respect to a center O and pairwise symmetrical with respect to the vertical plane xOy. Each pattern has three arcs participating in the production of the gradient which is required. That is, two outward arcs are located close to the center O at respective distances h.sub.1 and h.sub.2 from plane xOy and a return arc is spaced further from the center O and is located at a distance H.sub.3 from the plane xOy. Each arc has three section a, b and c, with the two end sections a and c having the same length being traversed by a current which has one-half the intensity of the current passing through the central section b.