Homogeneous current distribution in a coaxial superconductor with and without return current path

We have developed a theoretical method based on magnetic nux conservation b etween adjacent layers, One of the advantages of this method is that we can directly obtain twisting pitch and radius far realizing homogeneous curren t distribution in coaxial multi-layer superconductor. A set of the obtained twisting pitch and radius nas employed in a sample three-layer conductor c omprised of silver-sheathed multi-filamentary BSCCO-2223 tapes and the curr ent distribution was measured by Rogowski coil. Agreement between the exper iment and the theor on current distribution is quite remarkable. Using this theory, we analytically investigated influence of the manufacturing error of twisting pitch and radius on current distribution. The results revealed that the manufacturing errors of twisting pitch and radius have large effec t on current distribution and a suitable set of twisting pitch and radius a gainst manufacturing error ran be found. wee also investigated the relation ship between twisting pitch and current distribution in coaxial six-layer c onductor with return current path, The characteristics of twisting pitch in the conductor with return current path are different from those of the con ductor without return current path.