The experimental investigation of the Nb3Sn strands superconducting properties defining the stability of magnet systems

The computation of magnet systems stability requires the experimentally defined parameters characterizing the dependence of critical current (Ic) on temperature (T) and magnetic field (H). Testing results on the measurements of the above mentioned parameters for different kinds of multifilamentary commercially produced Nb₃Sn strands are presented. The strands produced for the application in model coils of ITER were analyzed in particular. The measurements of V(I) have been performed in the temperature range of 4.2 K-14 K in transverse magnetic fields from 5 T to 12 T. Voltage-current characteristics and temperature dependencies of resistivity measured in magnetic fields up to 12 T have been discussed. The parameters characterizing the process of increasing of electric field in the superconducting strands which accompanies the increase of transport current and the temperature, have to be defined experimentally, also.