$J_{\rm c}(B, T)$ Characterization of Commercial NbTi Strands for the ITER Poloidal Field Coils by Transport and Magnetization Methods

Commercial multifilamentary NbTi strands produced by the Russian Federation Domestic Agency for the ITER poloidal field (PF) coils PF1 and PF6 were characterized regarding by magnetization and transport measurements. The results of critical current measurements at magnetic fields in the wide range from 2 to 10 T and at temperatures from 3.5 to 7.5 K are presented. The experimental results were obtained at two laboratories; the two sets of data show a good match and demonstrate the high reproducibility of data. The current sharing temperature of the strands is between 5.9 and 6 K at 6.4 T at an operating current of 33 A. These results enable finding strand characteristic parameters for fits and lead to a database, which is essential for the future analysis of experimental data for the PF conductor performance.