AC losses in ultra-fine filament NbTi superconductors

Loss measurements are presented on an ultrafine filament composite and on a regular AC conductor, having "thick" filaments. The wires have been subjected to an alternating transverse magnetic field. An AC as well as a DC transport current have been fed through the wires. The magnetic field and the AC transport current have been sinusoidal functions in phase. The magnetization losses and the transport current losses have been measured separately. The critical current - according to the 10^-14Ωm criterium - and the quality factor n - according to V = V0(I/Ic)ⁿ- have been determined.