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Extended voltage–current characteristics of 13 optimized (Bi, Pb)2Sr2Ca2Cu3Ox/Ag multifilamentary tapes from four different manufacturers were extensively evaluated so as to extract the field-dependent Jc(H), the characteristic field Hp obtained from the relation Jc∼exp(−H/Hp), and the irreversibility field H*. Values of the self-field critical current density Jc(0 T, 77 K) ranged from 12 to 63 kA/cm2, Ic(0 T,77 K) from 11 to 139 A, Hp from 128 to 204 mT, and H* from 163 to 369 mT, this range thus being representative of present optimized composites. Self-field can strongly dominate Jc(H) in fields below 20 mT; thus, Jc(0 T,77 K) is a flawed parameter for characterizing tapes because of its very heavy dependence on self-field. We propose that a much better descriptor of tape performance is Jc(0.1 T,77 K), because it lies outside the self-field and weak-link-destruction regimes and clearly within the flux-pinning-controlled domain where the connectivity-determined active cross-section carrying current is constant. © 1999 American Institute of Physics.
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