Relation of Shunting Current at Cracked Part to Critical Current and <i>n</i>-Value in Multifilamentary Bi2223 Composite Tape

Abstract

Relation of transport current and n-value to collective crack-induced current shunting in BSCCO (Bi2223) multi-filamentary composite tape pulled in tension was studied experimentally and analytically. For analysis, the partial crack-current shunting model of Fang et al. was used by placing the collective crack as the partial one. It was shown that (a) collective crack-induced shunting current increases with increasing current (and voltage) and with increasing collective crack size, (b) the transport current normalized with respect to the transport current in noncracked state is described with the modified ratio of non-cracked area to overall cross-sectional area of superconducting filaments at low voltage where shunting current is low, while it deviates upward from the modified ratio at high voltage where the shunting current is enhanced, and (c) the enhanced shunting current acts to reduce n-value at high voltage. These features were similar to those of cracked coated conductor.