THE TRANSFER OF CURRENT BETWEEN A COMMON NORMALLY-CONDUCTIVE CONDUCTOR AND A NUMBER OF ELECTRICALLY PARALLEL SUPERCONDUCTOR CURRENT-CARRIERS

摘要

1,217,761. Electric couplings. SIEMENS A.G. 29 April, 1968 [29 April, 1967], No. 20311/68. Heading H2E. Electrical connection between a plurality of superconductors 1 and a common normally conductive conductor 5 is established by means of a like plurality of intermediate normally conductive conductors 2, an end of each superconductor 1 being embedded in an end of an intermediate conductor 2 in a cooling chamber 3 supplied with liquid helium at a temperature below the transition temperature of superconductors 1; from chamber 3 intermediate conductors 2 extend separately through insulation 11, e.g. polyethylene or nylon, their other ends being soldered to conductor 5 and being cooled in the connection region, by gaseous helium passing through a cooling block 6, to a temperature higher than that of cooling chamber 3. Conductor 5 is in turn connected to a further normally conductive conductor 8, which is cooled to progressively higher temperatures by liquid nitrogen at 9 and water at 10. Intermediate conductors 2 are identical and have resistances at least ten times that of the total resistance along their respective superconductors 1. Conductors 2, 5, 8 are made of high-purity Al. The cooled regions up to region 9 are enclosed in a vacuum jacket 21 enclosing a radiation protection jacket 22 and layers 23 of crinkled Al-coated polyethylene terephthalate foil. In a modification (Fig. 2, not shown) central portions of intermediate conductors 2 are cooled in an additional cooling chamber by, e.g. liquid hydrogen or cold helium gas; such portions may be provided with cooling vanes. The invention is described with reference to making connection to a cable comprising 127 superconductors, and may also be applied to superconducting coils and machines.