Low frequency AC losses in multifilamentary superconductors up to 15 tesla

Low frequency (1 Hz) ac losses were measured in a variety of A15 superconducting wires having different fiber geometries. Field modulations of ≤ 1 tesla were superimposed on a fixed background field up to 15 tesla. Losses were measured for Nb3Sn in continuous fiber, modified jelly-roll, In Situ, and powder metallurgy processed materials, and for Nb3Al powder metallurgy processed materials. The results are compared with dc magnetization measurements. The losses are purely hysteretic at these low frequencies, scale with Jc(above ∼ 3 tesla), and are reduced substantially by twisting for all the materials. The lowest losses are observed for the Nb3Al wires.