The Jc limit of multifilamentary Ag/Bi-2223 tapes

To improve on present critical current (J(c)) performance, multifilamentary Ag/Bi-2223 tapes with a large range of reduction rates were manufactured. The relative core mass density D was calculated, dependent on the measured geometric dimensions of the tapes. Experimental results, D vs. J(c), D vs. maximum pinning force density F-max, and D vs. irreversible magnetic field B-irr, are quantitatively formatted. In particular, the magnetic field dependence of J(c) is critically dependent on its core density. If the core density increases by 10%, J(c) of the tapes in this experiment is enhanced by as much as 100%. Therefore, in the present state of the technological process for manufacturing Ag/Bi-2223 tape, increasing the core density is clearly a significant strategy in improving the electronic and magnetic properties of the tapes and enhancing the capacity for carrying current at high magnetic fields. The limit of the bulk self-field-J(c) can be calculated by the relationships of J(c) vs. D. The limit is estimated to be on the order of 200 kA/cm(2) for multifilamentary Bi-2223 tapes, which was supported by magneto-optical (MO) magnetization measurements results. It is a hard task to approach this limit with the present state of the art in manufacturing Ag/Bi-2223 tape, and it is the time to suggest some new ideals for Bi-2223 tapes to promote large-scale applications.