Improved measuring procedures and interpretation efforts have shown that the critical state model is fully applicable for describing the behaviour of HTS tapes for power applications. By this means, we could consistently analyse magnetic and transport measurements and study possible inhomogeneities and geometrical peculiarities in BSCCO-2223 tapes. Examples of such an analysis are given in this contribution. Losses in multistrand conductors require a more complex modellization and further development of the experimental procedures; the results of a.c. transport measurements on a 13 m long, multilayer, prototype conductor sample are also discussed here.
We study the effects of surface columnar defects created along about 5% of the sample thickness by means of 0.25 GeV Au ions at different doses on Bi 1.8 Pb 0.33 Sr 1.87 Ca 2 Cu 3 O y high-quality tapes on the vortex dynamics in the sample bulk. Strong phenomena of vortex localization inside the bulk are revealed by shifts of the irreversibility lines ͑IL's͒ as well as by their after-irradiation shape. The enhanced IL's exhibit specific characteristics, such as a Bose-glass-like behavior up to quite high fields, with a dose-dependent onset point. Moreover, the irreversible regime expands with decreasing defect density. Such results are consistent with the setting up of confined vortices morphologies. Experimental data concerning the IL with the field orthogonal to the columnar defect direction as well as critical current density enhancements are also reported and discussed. ͓S0163-1829͑99͒01205-9͔
We have investigated the effect of aspect ratio and current on the self-field critical current of Ag-sheathed Bi-2223 composite tapes. We have fabricated assemblies of monofilament tapes with different aspect ratio and current capacity. In such a manner, we could study the effect of the composite geometry on the self-field suppression of the critical current while maintaining the quality of the superconducting filaments constant. We find that a large aspect ratio is favorable for achieving higher self-field critical currents which is consistent with a reduction of the self-field. We have also used a modified configuration of several tapes with opposing currents to reduce the perpendicular component of the self field. As a consequence, we have observed large enhancements of the critical current at zero applied magnetic field, and have also been able to reveal the magnetic field dependence of the critical current at low magnitudes of the external field where the self-field usually dominates the externally applied field. We have studied these effects in several tapes with different levels of current capacity.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.