To provide a bronze-process Nb3Sn superconducting wire which will not cause superconducting characteristics to deteriorate; and to provide a precursor (precursor for manufacturing a superconductive wire) for providing such a superconducting wire.
This precursor is provided with a superconducting matrix part, having a plurality of Nb or Nb base alloy filaments arranged inside a Cu-Sn base alloy, and has stabilized copper arranged in its outer periphery. In the precursor, a reinforcing layer formed of Ta or a Ta base alloy is interposed between the superconducting matrix part and the stabilized copper; and when it is assumed that the distance from the center of a cross section of the precursor to the outer surface thereof, the distance from the center of the cross section to the inner surface of the reinforcing layer, and the distance from the center of the cross section to the outer surface of the reinforcing layer are R, r1 and r2, respectively, relations (1): 0.4r1/R0.8, (2): 0.55r2/R0.95 and (3): 0.05(r2-r1)/R0.22 are satisfied.
ZAITSU TAKASHI
KATO HIROYUKI
MURAKAMI YUKINOBU
JAPAN SUPERCONDUCTOR TECH
Tadashi Sugakawa
Osamu Futakuchi
Hiroaki Ito