HYSTERESIS LOSSES IN BI-2223 SUPERCONDUCTORS

In this study we examine magnetic hysteresis losses in Bi-2223 hulk su perconductors. Two kinds of hysteresis losses were found in the sample s: losses in superconducting grains and losses due to the intergranula r weak link structure, Total losses at 77 K were about an order of mag nitude higher than losses in grains, This indicates the domination of intergranular hysteresis losses with respect to intragrain losses. To understand the experimental results, we numerically simulated the beha vior with model specimens, where different kinds of Josephson junction arrays corked as the models for the intergrain system. A special atte ntion was paid to the influence of porosity, second phase particles, a nd magnetically induced granularity on the hysteresis losses. If at le ast one of the inhomogeneity sources was present, the magnetization of the array could exhibit remarkable hysteresis and losses.