Critical current properties in multifilamentary Bi-2223 tape produced by the over pressure processing

Investigation is done on the effect of ConTrolled Over Pressure (CT-OP) processes on the critical current properties in multifilamentary Bi-2223 tapes. It is found that the critical current density at low magnetic fields is remarkably improved by the new CT-OP process. This result with those on irreversibility field and n-value are compared with the numerical calculation based on the flux creep and flow model. The analysis reveals that the most probable value is increased, although the statistical distribution width is increased for the flux pinning strength. This result indicates that the critical current density at high magnetic fields is deteriorated by the widened distribution. If such an inhomogeneity can be reduced to the level of previous tapes by improving the CT-OP process, the high field performance is shown to be significantly improved. (C) 2007 Elsevier B.V. All rights reserved.