Influences of winding pitch on transverse-field loss of multifilamentary wire measured by a simple electromagnetic method with configuration of a double-layer non-inductive sample coil

We have proposed a simple electromagnetic method of ac loss measurements for superconducting wires in various types of electromagnetic environments. So far, the samples were closely wound as a double-layer non-inductive coil. In this study, we prepare some sample coils of NbTi multifilamentary wire with different winding pitches, and measure the ac losses in a transverse magnetic field by the simple electromagnetic method. We evaluate the influences of winding pitch in the sample coils on the transverse-field losses in comparison with those by a conventional pickup-coil method and theoretical prediction. We have an experimental result that the simple electromagnetic method is useful to measure the transverse-field loss even for loose windings with a turn-to-turn spacer. Taking into account a demagnetization effect, we also obtain a conclusion that the ac losses can be plotted on a master curve for the maximum level of local magnetic field applied to sample wire.