Predictive model for critical current density of Ag-sheathed Bi₂Sr₂Ca₁Cu₂O₈ composite tapes with fabrication defects

Fabrication of long Ag-sheathed Bi₂Sr₂Ca₁Cu₂O₈ composite tapes is sometimes accompanied by the distribution of large bubble-type defects located at relatively uniform intervals along the length of the conductor. The size, shape and number of these defects dictate the critical current density and eventually the overall quality of the tape. The effect of defect size and concentration on the overall critical current density is theoretically modelled. Using experimental data on the transport properties of short conductor samples with a defect of known dimensions, the model can be used to predict the critical current density of a long conductor tape by visual inspection of the number, size and location of these defects along the conductor length.