Electrical characterization of the NbTi strand for the ENEA stability SEx-up experiment

A NbTi 36 strands cable-in-conduit conductor will be wound in a coil (SEx-Up Experiment) in the framework of a study of the performance of a subsize cable for the Poloidal Field Coils of ITER. The basic multifilamentary NbTi strand has been extensively characterized. The electrical characterization enabled us to get a database, essential for the future analysis of the experimental data, and to find the strand characteristic parameters for the I_c(H, T) fit. We measured critical temperature vs. applied magnetic field, transport critical current vs. applied magnetic field, and magnetization vs. applied magnetic field and temperature. The last measurement gives the hysteresis losses, and implicitly the critical current values; magnetization data have been therefore correlated with direct J_c transport measurements, taking into account the self-field effect. A good match has been found, so magnetization data allowed us to enlarge the range of field and temperature toward regions in which the transport measurements are more difficult, namely low fields or high temperatures.