Self fields and current distribution due to DC transport currents on Ag-sheathed (Bi,Pb)2Sr2Ca2Cu3Ox tapes

Using a scanning Hall sensor magnetometry with an active area 50 mu m X 50 mu m, we investigate the self-field distribution at 77 K due to DC transport currents subjected to the programmed current sequence in zero external field on the surfaces of Ag-sheathed (Bi,Pb)(2)Sr2Ca2Cu3Ox monofilamentary and multifilamentary tapes, We derive the field slope from the measured magnetic profile and relate it to the current distribution in the superconductor. The results for the monofilamentary tape are well explained by the Bean model on the assumption of an elliptical superconductor core, which claims that the current distribution is assigned to J(c), -J(c) and/or 0 in the superconductor and the border of the current distribution forms concentric ellipsoids with the same aspect ratio of the sample. There is a resemblance in the self-field distribution and accordingly the current distribution between the monofilamentary tape and the multifilamentary tape. The multifilaments behave as a solid superconductor under DC transport currents so that the current distribution cannot be equalized in the filaments. (C) 1997 Elsevier Science B.V.