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

Experimental results showing I-c versus length for long Ag/Bi(Pb)-2223 mult ifilament tapes are presented. The results are obtained using a contact-fre e 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 stud y 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 sig nal pattern and the spatial resolution is demonstrated to be as good as a f ew mm, The non-destructiveness is generally good. The first cycle/re-coilin g of a tape may decrease the critical current by less than 2%, and each fol lowing 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 supercon ductive properties of the final product and is therefore a good tool for pr oduct development and quality control.