Recent development of the Cu/Nb-Ti superconducting cables for SSC in Hitachi Cable, Ltd

In these few years, Cu/Nb-Ti superconducting cables for the dipole magnets of SSC projects have been developed in the industrial scale in Hitachi Cable, Ltd. The features of these developed conductors are as follows. (1) The diameter of Nb-Ti filaments is very small, 4-6 μm. (2) The critical current density (Jc) is very high, 2,850-3,050 A/mm2 at 5 T on wires, 2750-2950 A/mm2 at 5 T on cables in industrial scale. The champion Jc of wires is 3,460 A/mm2 at 5 T in the laboratory scale. (3) The RRR Residual Resistivity Ratio values of developed cables is very high, approximately 200, due to the newly developed high purity Oxygen Free Copper (OFC). (4) The conductors have been wound to the 1 m length dipole magnet in Hitachi Ltd., and it has generated 6.7 T in the central magnetic field at 6,595 A. The Cu/Cu-Mn/Nb-Ti composite wires which avoid the possibility of electrical coupling of the filaments have been produced in laboratory scale. The RRR of the copper stabilizer and Jc properties have not degraded because of no metallurgical reactions between Cu and Mn, Nb-Ti and Mn. 7 refs., 9 figs., 4 tabs