GB1356458A - Superconductor coils - Google Patents

Abstract

1356458 Superconductor coils; particle accelerators SIEMENS AG 16 Nov 1971 [16 Nov 1970] 53242/71 Headings H1P and H1D Normally conductive spacers, arranged between adjacent turns of a superconductive winding from which they are insulated, are connected to form a protective inductive circuit. As shown, Fig. 1, a quadrupole magnet comprises four elongate saddle-shaped coils 1 to 4 arranged on a non-magnetic steel carrier 5. Each coil comprises an elongate core 10 of noble-steel or plastics round which are wound four winding sections 6 to 9 separated by wedge shaped spacers 11 to 16. Each winding section comprises a plurality of turns of superconductor tape, the number of turns being greatest in the outer section 9 and least in the inner section 6. The sections are made up to the same cross-section by means of layers of plastics tape inserted in the winding. The wedge shaped spacers 11 to 16 are joined at each end by bow shaped connectors 18 20, 22 (17, 19, 21) to form three closed loops which absorb energy from the winding if it goes normal. Each spacer is insulated from the carrier 5 by a folded plastics tape placed over its edge, and if necessary this tape can cover the sides of the spacer to insulate it from the superconductor winding. The coils may be produced by winding superconductor strip and plastics tape round the core 10 to produce section 6, placing the spacers 11, 12 against the straight edges and then continuing winding to produce section 7. The other spacers and coil sections are similarly applied to produce the saddle shaped coil. The connectors are of copper soldered to the spacers. The superconductor strip may comprise a tape having a Nb-Sn layer covered with a thin stabilizing layer of Cu. Instead of being connected to form a plurality of loops the interconnections between the spacers may be arranged so that a single loop is formed, Fig. 3 (not shown). An ohmic resistor may be connected in such a circuit and positioned externally of the liquid helium or externally of the cryostat. A switch may be provided to disconnect the current supply to the superconductor coil in response to the voltage increase produced when part of the coil goes normal. The coil may also be constructed of superconductor wire.