高密度20万kW級超電導発電機·界磁巻線用NbTi超電導素線·導体の開発

The NbTi superconducting strands and cables for the field winding of 200MW class high energy density type superconducting generator are developed. They are composed of Cu/Cu-10wt%Ni/Nb-46.5wt%Ti superconducting strands and the 10kA (at 5T) class 9-strand compacted cables. The diameter of strands is 1.33mm, and the 9-strand compacted cables are 2.4mm thick and 6.0mm wide. In order to produce high current density NbTi strands, we made strands under the controlled aging heat treatments, the total and final strains, and the strains between heat treatments, by using large scale extruder. Moreover, in order to produce high stability and low A. C. loss NbTi strands and cables, the matrix ratio of strands and the cross sections of strands are optimized. The current density of NbTi filaments for the 4 times aging manufactured 1.33mm dia. strands was Jc = 3150A/mm2 at 5T, 1150A/mm2 at 8T. The critical current of the class 9-strand compacted cable is 10.7kA at 5T. The A. C. losses of the final compacted cables are less than 100kW/m3 at 5T, 5T/s, they are decreased to less than half of the target of the A. C. loss value ( 2) increased about 40% at the operation mode current of the superconducting generator.