IMPROVEMENTS IN OR RELATING TO ELECTRICAL CONDUCTORS

摘要

1205130 Super-conductors SCIENCE RESEARCH COUNCIL AND IMPERIAL METAL INDUSTRIES (KYNOCH) Ltd 27 March 1969 [3 April 1968] 16023/68 Headings H1A and A4D An electrical conductor comprises a plurality of filaments of super-conductor material separated from one another by a matrix of non-superconductor material, each filament having a maximum thickness of 0À005 cm and being twisted or transposed about the other filaments with a twist or transposing length L = 104 x 4 (kJdp)¢/a(B)¢ wherein k is a space factor equal to the ratio between the linear dimensions of super-conductor and those of super-conductor plus matrix materials in a direction parallel to the magnetic field to which the conductor is to be subjected, J is the critical current density in amps/cm2 of the superconductor material, d is the average thickness in cms of each filament perpendicular to the magnetic field, p is the resistivity in ohm-cms of the non-super-conductor material separating the filemants from each other and having the highest electrical resistance, is the rate of change of field in gauss/second to which the conductor is to be subjected and a is a number greater than 3 and sufficiently large for the variation in flux rate of range along the length L divided by the mean flux rate of change B along the length L to be less than the thickness d divided by the thickness of the conductor perpendicular to the field. The matrix material may be a copper-nickel-manganese alloy; the super-conductor material an alloy comprising niobium, titanium, zirconium, hafnium and/or tantalum, or Nb 3 Sn. The super-conductor is made by inserting a billet of the super-conductor material in a can of matrix material, extruding and reducing, packing the product in a further can of matrix material, extruding, reducing and annealing.