On the effect of NiW on the inductance and AC loss of HTS cables

The impact of Ni-5at%W substrates on ac loss and inductance of HTS cables was examined. Two 1.2-m prototype cables were made with stainless steel laminated BSCCO tapes and were wound on a 25.4 mm diameter former. Each cable consisted of two layers of 15 BSCCO tapes wound at opposite lay angles and has an estimated critical current of 3000 A at 77 K. One cable had four additional layers of 4.8 mm wide Ni-5at%W tape co-wound with the BSCCO tapes to simulate a commercial second generation HTS cable. The Ni-5at%W tapes had the same width as the BSCCO and a thickness of 50 microns. Through the use of a coaxial copper ground, the cable inductance was measured at room temperature and liquid nitrogen (77 K) using high frequency rf measurement techniques. Experimental results for the cable inductance and ac loss were compared against numerical calculations to determine the significance of the Ni-5at%W substrate contribution. Results indicate that inductance and ac loss changes from these substrates in commercial cables should be small.