AC losses in multifilamentary Bi-2223/Ag tapes subjected to bending strains H. Suzuki a , J. Ogawa b , M. Ciszek a,c , O. Tsukamoto a, * a Yokohama National University, Faculty of Engineering, 79-5 Tokiwadai, Hodogaya-ku, Yokohama 240-8501, Japan b Graduate School of Science and Technology, Niigata University, Ikarashi 8050, Niigata 950-2181, Japan c Polish Academy of Sciences, Institute of Low Temperature and Structure Research, ul Oko ´ lna 2, 50-422 Wroclaw, Poland Received 23 November 2004; accepted 17 January 2005 Available online 25 July 2005 Abstract Electrical power devices, e.g. motors, power transmission cables, transformers, etc. are the most promising, and nowadays the most technologically advanced, applications of high temperature superconductors (HTS). Multifilamen- tary HTS tapes (usually Bi-2223/Ag composites) are used in forms of various in shape coils, therefore are subjected to different kinds of mechanical stresses. This leads to some changes in physical parameters of superconducting material, mainly in the critical current density, and thus in the dissipated electromagnetic energy. In general, when a supercon- ductor is carrying an AC transport current and simultaneously subjected to an external AC magnetic field, the total dissipated energy can be considered as a sum of components, the transport loss and the magnetization loss. In this work we report some experimental results related to the total AC loss characteristics of Bi-2223 tapes and their dependencies on bending strains. An external magnetic field, in phase with an AC transport current, was directed parallel to the wider surfaces of the samples. The total AC losses in the Bi-2223/Ag tapes were measured by means of a calorimetric method. Obtained experimental data are compared with the critical state model predictions for total losses behavior in presented here experimental conditions. Ó 2005 Elsevier B.V. All rights reserved. PACS: 85.25.Kx; 74.60.Jg; 74.25.Ld Keywords: Superconducting tapes; AC losses; Critical currents 1. Introduction At present the mostly developed high tempera- ture superconducting (HTS) composite conductors are multifilamentary tapes based on the Bi-2223 0921-4534/$ - see front matter Ó 2005 Elsevier B.V. All rights reserved. doi:10.1016/j.physc.2005.01.068 * Corresponding author. Tel.: +81 45 339 4124; fax: +81 45 338 1157. E-mail address: osami@tsukalab.dnj.ynu.ac.jp (O. Tsuka- moto). Physica C 426–431 (2005) 1333–1338 www.elsevier.com/locate/physc