| 摘要 |
A superconducting coil comprises superconductive wire turns 14 embedded within a resin 16 with an outer layer 18 of resin 16 filled with filler material 20. The coil includes a thermally conductive cooling layer 22 interposed between the outer surface of superconductive wire turns 14 and the filler layer 18. The cooling layer 22 is thermally connected to a block 24 cooled to a temperature below that of the superconductive wire critical temperature. The block 24 may be integrally formed, possibly by a single extrusion process, with the thermally conductive layer 22. The block 24 may include a tube 26 through which cryogenic fluids may pass. The cooling block 24 may also be embedded in the resin 16. The thermally conductive layer 22 may be perforated and formed of anodised aluminium material. The filler material 20 may be glass fibre or glass beads. Alternatively a cold finger of a refrigeration unit may extend to make direct thermal contact with a solid thermally conductive block member 24. Also disclosed is a method of making coils with a cooling layer comprising winding a superconductive wire into a mould, applying a cooling layer over at least part of the circumference of the superconductive wire wound coil, wrapping a filler layer over the cooling layer and impregnating the whole structure, formed within the mould, with a resin. The superconducting coil may be used in magnetic resonance imaging MRI or nuclear magnetic resonance NMR systems. |
