Flux distributions in jointed Bi₂Sr₂Ca₂Cu₃O_10+δ tapes

Superconducting joints between monofilamentary, Ag-sheathed Bi₂Sr₂Ca₂Cu₃O_10+δ tapes were investigated by means of magneto-optic imaging. Two types of joint were studied; one joint with direct contact between the tape cores, and the other one with an Ag layer between them. The local flux distributions directly reveal the obstacles hindering the current flow through the joints. The direct contact of the tape cores provides joints which can carry about 80% of the current of the original tape, whereas the joints with the Ag layer are considerably worse. This difference becomes even more drastic in applied magnetic fields.