The effect of intermediate pressure in the OPIT fabrication on the currentpaths and the current carrying capability of Bi-2223 tapes

Intermediate pressing techniques in the OPIT fabrication of high temperatur e superconducting Bi-2223 tapes have evolved from plane strain pressing int o more continuous methods such as rolling, continuous pressing and eccentri c rolling, In this study one of the most promising methods have been invest igated, and novel techniques to characterize the tape quality have been tak en into use: magneto optical imaging was used to detect the current paths i nside the superconducting tape and to reveal differences between tapes that were intermediately pressed differently. The filaments in the tapes were e xtracted and shattered by ultrasonic vibration in order to check the size d istribution, Bending tests were performed to show differences in current ca rrying capability as a function of an applied external load, It is shown ho w the pressing load greatly influences the current carrying capability of t he finished high temperature superconducting tapes. By selecting the right pressing method it is possible to optimise the I-c and J(c) values.