| 摘要 |
Two opposite iron core pole pieces of a magnetic resonance medical imager generate a static magnetic field in a patient imaging volume disposed between the pole pieces. Gradient coils are positioned in the face of a pole piece. Thin disc shaped (42, 44) or ring shaped (41) ferromagnetic parts laminated of layers cut favorably from transformer sheet material are attached to the face of the pole piece. Each layer is electrically insulated from adjacent layers and surfaces by enamel or fixing glue. To reduce eddy currents in these layers, narrow, radially oriented slots (43, 45) are cut in these layers before lamination. The slots are oriented in the adjacent layers so as not to coincide resulting in improved conduction of the magnetic flux in the imaging volume during the production of gradient magnetic fields by the gradient coils.
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