An experimental study of fine filaments NbTi strand for fast cycled magnets

The Italian Institute for Nuclear Physics is working on the development of fast cycled dipoles for the Facility for Antiproton and Ion Research SIS300 synchrotron at Gesellschaft fur Schwerionenforschung, Darmstadt. In this framework the development of high current and low ac loss superconducting wires is an important step of the R&D. The main technique to attain these features is to develop line filaments for the strands and to design suitable resistive barriers among filament islands within the strands. In this paper, we study a newly developed wire in terms of critical currents and ac losses. The critical current is obtained from magnetization cycle and direct transport current. The ac loss mechanisms caused by the interfilament electromagnetic coupling is related to the rho(et), the transverse resistance between adjacent filaments. We measure rho(et) through ac susceptibility technique.