AC losses in HTSC bulk and tapes: A review

After the advent of high temperature superconductors (HTSC), much research and development have been carried out and currently these materials are on the verge of being used in the power engineering applications at a commerci al scale. In such applications, the ac losses of superconductors are regard ed as one of the most important design parameters that guide the fabricatio n of the devices. There are different methods for the determination of such losses. This article describes some of the widely used methods and discuss es the results on the ac losses of bulk HTSC compounds and single and multi filamentary tapes. The nature and origin of the losses in these materials a nd their dependence on various physical entities like applied field, freque ncy, and temperature have also been dealt with in detail. Gap areas have al so been identified in which further research is needed in order to facilita te the design and fabrication of commercially usable devices with superior performance.