Critical current measurements on long BSCCO tapes using a contact-free method

Experimental results showing I/sub c/ versus length for long Ag/Bi(Pb)-2223 multifilament tapes are presented. The results are obtained using a contact-free method (Hall probe) measuring the shielding and remanent magnetic fields created by tapes when exposed to an external magnetic field. The main goal of this paper is to study the potentials of the applied method and the study includes reproducibility, resolution, non-destructiveness and usefulness in the production of tapes. The results show that the reproducibility is so high that the method can be used to identify individual tapes by their signal pattern and the spatial resolution is demonstrated to be as good as a few mm. The non-destructiveness is generally good. The first cycle/re-coiling of a tape may decrease the critical current by less than 2%, and each following cycle is observed to have an effect of less than 0.5%. This contact-free method offers the tape manufacturer a detailed picture of the superconductive properties of the final product and is therefore a good tool for product development and quality control.