TRAPPED MAGNETIC-FIELDS IN MELT-TEXTURED YBCO

The surface of melt-textured bulk YBCO samples, cooled at liquid-nitro gen temperature, was mapped with an automatic Hall probe-based system to study the spatial distribution of trapped magnetic fields. Such a m agnetic characterization offers detailed information about the granula r structure of differently prepared samples. Both axial and tangential trapped magnetic-field components were measured. the axial component of the trapped magnetic field allows one to obtain the number of grain s, their shapes, their dimensions and their locations, while measureme nts of the tangential component of the trapped magnetic field give com plementary information on the grain positions. Intragranular critical current densities were estimated by comparing experimental trapped mag netic-field profiles with theoretical ones calculated using the critic al-state model.