Optimum reduction of self field effects in a Bi-2223 stacked superconducting bus bar

High Tc Superconductors, such as Bi-2223, have been promising candidates fo r an electrical bus bar because bus bar has relatively low self magnetic fi eld. It has been found that the critical current of Bi-2223 stacked tapes i s much less than the total summation of critical currents of each tape, whi ch is mainly attributed to the self magnetic fields. Furthermore, since the critical current degradation of Bi-2223 tape is greater in the normal magn etic field (to the tape surface) than in the parallel one, detailed magneti c field configurations are required to reduce the self field effects. Conce ptually, by rearranging each stacked tape properly, the self field effects could be minimized. In this paper, we calculate the self field effects of a stacked conductor, defining self field factors of normal and parallel magn etic fields to the tape surface. And we propose an optimum shape of octagon al structured bus bar which has minimum self field effects.