A simple electromagnetic method of cyclic loss measurement for superconducting wires in a combined alternating transverse magnetic field and transport current

We measured cyclic losses in a superconducting wire, carrying alternating t ransport current, simultaneously exposed to an alternating transverse magne tic field. Samples of Bi-2223 Ag-sheathed tapes have configuration of a dou ble-layer non-inductive coil, which itself is a pickup coil to measure the AC losses. Potential taps were attached to both terminals of the sample coi l. The external field was applied along the axis of the sample coil. In thi s procedure, we can estimate an averaged Poynting's vector on a cylindrical surface between the two layers by means of signals from a pair of the pote ntial taps and from pickup coils for the external magnetic field and the tr ansport current. We can also measure a magnetization and an extended transp ort-current components of AC losses in addition to a total cyclic loss for a combined alternating external field and transport current. Obtained resul ts are compared with numerical predictions of the critical state model taki ng into account the magnetic field dependence of critical current density. (C) 1998 Elsevier Science B.V. All rights reserved.