Development of fine filament NbTi superconducting strands for magnet systems of fusion reactors

Bochvar Institute (VNIINM) has developed and produced fine filament NbTi su perconducting strands of several layouts for International Thermonuclear Ex perimental Reactor (ITER) poloidal field (PF) coils. The strands, having outer diameter of 0.7 mm and filament diameter of 6.5 m um, have been manufactured both by single and double stacking. Strand layou ts distinguish by Cu/Sc ratio and a filament zone arrangement in cross-sect ions, one of them includes CuNi resistive barriers to reduce AC losses in o perating condition of ITER magnet system. The results of comparative investigations on critical currents, critical cu rrent density, AC losses, critical temperature of the strands are presented . Two strands of these layouts are supposed to be used in the experimental cable for the model coil of SULTAN facility. (C) 2001 Published by Elsevier Science B.V.