The Jc Limit of Multifilamentary Ag/Bi-2223 Tapes

To improve on present critical current (Jc) 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. Jc, D vs. maximum pinning force density Fmax, and D vs. irreversible magnetic field Birr, are quantitatively formatted. In particular, the magnetic field dependence of Jc is critically dependent on its core density. If the core density increases by 10%, Jc 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-Jc can be calculated by the relationships of Jc vs. D. The limit is estimated to be on the order of 200 kA/cm2 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.