Development of (Nb, Ti) 3 Sn and Nb-Ti conductors for 15 T superconducting magnet of 40 T class hybrid magnet
Tube processed (Nb, Ti) 3Sn and NbTi conductors have been developed for a 15 T class superconducting magnet with a 400 mm clear bore of a 40 T class hybrid magnet. Prior to testing the actual conductor, the transverse compressive stress effects on the critical current ( Ic) of the (Nb. Ti) 3Sn conductors were studied using a 1/7 scale reduced conductor. The Ic of the samples with clearance of gap length of over 0.3 mm between Cu-housings and (Nb,Ti) 3Sn monolith reached over 90% of unloaded Ic( Ic0) at 14 T and 60 MPa of the transverse compressive stress. Based on the above-mentioned results, a new structure for full-scale Cu-housing (Nb,Ti) 3Sn conductors has been designed and fabricated. Fabricated (Nb, Ti) 3Sn conductors flowed more than 3870 A at 15 T and had 300 M Pa of 0.2% proof stress. All these values exceeded the values in the specification with a good margin.