Comparison of some electrical properties of Bi(2223)/Ag tapes at 4.2K and 77K

摘要

Composite Bi(2223)/Ag tapes having different cross-section layouts (single core, multifilamentary, concentric or multilayered) exhibit high critical temperatures ( T{sub}c≈100 K) and high upper critical magnetic fields (B{sub}(c2)> 150 T). These properties make them feasible for use in two practical spheres: (i) as dc or ac power cables working at 77 K in low self-field configurations or (ii) as insert coils for high field magnets (B > 20 T) at 4.2-20 K. The aim of the following contribution is to give a brief review on some interesting differences in the behaviour of Ag-sheathed Bi(2223) superconducting tapes at liquid helium (4.2 K) and/or at liquid nitrogen (77 K) temperatures. The comparison mainly concerns the hysteresis of the critical current (I{sub}c) dependence on the external magnetic field (B) as well the anisotropy in current carrying capability and silver matrix magnetoresistance depending on the orientation of the tape in the magnetic field. The discussed problems are illustrated by some examples of Bi(2223)/Ag multifilamentary tapes that were prepared and examined in our Institute during the search for optimum conditions in the process of preparation by the PIT method [1].