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Abstruct-The ac losses of (Bi,Pb)SrCaCuO tapes and wires and a YBaCuO tape have been measured in self and applied fields. The transport losses of the YBCO tape are much higher than any predictions using the critical state model. In this situation, the Bi-2223 wires and twisted tapes have the lowest losses. In applied perpendicular fields the losses of all conductors are currently too high and should he reduced. The Bi-2223 wires are the most flexible and provide the greatest scope for further loss reduction in the short to incdiuni term.

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Measurements have been made of the a.c. self-field losses in PbBi2223 tapes with different core/sheath configurations. Three different tapes have been measured, two monocore tapes with core thicknesses of 25 µm and 80 µm and a multifilamentary tape of overall thickness 200 µm. The a.c. losses have been obtained by measurement of the loss electric field E l at a sufficient distance (three times the tape half-width) from the tape axis. Measurements of the spatial dependence of the loss and inductive electric fields E l (x ) and E i (x ) have also been made. The results indicate that the 'thin' monocore tape can be adequately described by the thin-rectangle geometry whilst the behaviour of the 'thick' monocore tape lies in between those of the thin rectangle and thin ellipse. The behaviour of the multifilamentary tape follows closely that of a monocore ellipse tape indicating that there is a strong interaction between the filaments.

The phase content and grain alignment of individual filaments in Bi2223 multifilamentary tapes have been successfully analysed by means of a micro-x-ray diffraction system. According to the 2223 phase formation rate and texture, filaments can be divided into three groups. The filaments in the centre part of the tape have higher 2223 phase content and better texture due to their thinner, flatter shape. The filaments near the tape edges are poorer because of their low density and irregular shape. The strong variation in filament shape and density could be two of the most important factors that affect the homogeneity of 2223 phase conversion and texture quality. Using a more reactive powder, a harder sheath and making heat treatment under 7% oxygen, as well as using rectangular wire to start the rolling process, can all increase the filament uniformity and enhance the tape's Jc value.