AC Loss in High-Tc Superconductors

Abstract

There are three kinds of AC losses in superconducting wires, transport current losses, magnetization losses and total losses. The first losses are caused by the AC transport currents flowing in the wires, the second caused by the AC external magnetic fields which the wires are subject to and the third caused by the combination of the transport currents and external magnetic fields. The measuring methods are divided in electric and calorimetric methods. Generally speaking, the electric methods are sensitive and precise but have some problems to measure false losses if the electromagnetic environments of the wires are not well defined. On the other hand, the calorimetric methods can measure the real losses but are not so sensitive or precise as the electric methods. In the paper, electrical methods for AC loss characterization of the HTS wires are reviewed. The AC loss data of Bi2223/Ag sheathed and YBCO tapes are also presented and the loss characteristics are studied.