Abstract
Abstract A study of the DC I–V curves of bifilar BSCCO/Ag tapes at 77 K is presented. Tapes under study were carrying DC transport current and exposed to external AC (0–20 mT, 50–400 Hz) or DC (0–20 mT) magnetic fields perpendicular to the plane of the tape. The measurements were carried out with bifilar tape to avoid the influence of the self-field. The measured I–V curves are well described by power law in the range of electric field 0.1–10 μV/cm. The AC field affects the I–V curves in a much stronger way than the DC field. The application of the AC field results in a linear decrease of the critical current (criterion 1 μV/cm) independent of the frequency of the magnetic field. The exponent n also exhibits a strong dependence on the AC magnetic field decreasing with increasing AC field amplitude and increasing with increasing frequency. The results are interpreted by assuming a confinement of the DC transport current in the central AC field free region of the tape. A low current density is assumed to flow in the region to which the AC magnetic field has penetrated.
Published Version
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