Anisotropy of transport properties normal and parallel to the tape plane in Bi-2223/Ag tapes

Abstract

We have performed transport, resistivity and critical current measurements on Bi-2223/Ag tapes with current directions both parallel and perpendicular to the tape plane in magnetic fields up to 7 T and 50cTc250 K. We find that the resistivity along the tape normal (nominal c-axis in a textured tape) is metallic, scales with the in-plane resistivity at all fields and is dramatically reduced from single crystal c-axis values. Similarly, the critical current along the tape normal exhibits magnetic field and field orientation dependences similar to those for current flow along the tape plane. These results indicate that current flow along Cu02 planes dominates current transport even along the tape normal in highly textured tapes.

Current transfer and initial dissipation in high- superconductors

“…A pronounced role of grain boundaries in charge transport phenomena is simply a consequence of the high effective resistivity of a boundary, compared with the resistivity of the volumetrically predominant and, on averaging, homogeneous intragranular background. This qualitative relationship between the intragranular and grain boundary resistivities, documented to exist both in YBCO and in BSCCO systems [50,73,75] has been pointed out in numerous reports as a plausible source of the inhomogeneous distribution of normal and superconducting currents. In particular, it has frequently been suggested that the actual current lines bypass all high-angle boundaries, or boundaries substantially degraded by other causes, owing to their high resistances (decisive for normal transport) or because of their small Josephson critical currents (decisive for supercurrent transport).…”

A numerical model for stability considerations in HTS magnets

“…The anisotropy of a material can be expressed in terms of thermal conductivity and electrical resistivity with tensors {λ uv } and {ρ uv }(J), u, v = 1, 2, 3 [33][34][35].…”

“…Data for the resistivity of silver were found in [49]. For the resistivity of the Bi-2223 material, we used equation ( 8) with ρ r (T ) = 10 µ m [35]. J (T ) and J r (T ) were found by fitting equation (8) to the power law, equation (7), with n = 10 in the interval 0.7J c (T ) J 1.2J c (T ).…”

Study of HTS Wires at High Magnetic Fields

“…1 field. Earlier 1G tapes have been tested at various temperatures in both field directions [7,8]. Angular measurements on 2G have been performed at higher temperatures [9,10].…”