Contactless measurement of hysteretic transport AC losses in multifilamentary BiSrCaCuO-2223/Ag tapes

We demonstrate how the hysteretic transport AC losses in multifilamentary superconducting tapes can be determined in contactless way using a pick-up coil attached to the tape wide face. To transform the pick-up coil signal into the true loss signal, certain assumptions about the distribution of current in the tape section must be adopted. We show that the simple assumption of uniformly distributed current density gives results that are correct within 25%. A more complex model based on distribution of remanent currents brought the agreement between contactless and direct measurement to within 10%. Since the coil signal is directly proportional to the number of turns, the method provides increased sensitivity compared to that with voltage contacts. This can be helpful when investigating tapes with extremely low AC losses. Finally, we discuss how the comparison of direct and contactless methods can give information about filament nonuniformity. (C) 1998 Published by Elsevier Science B.V. All rights reserved.