HTS twisted stacked-tape cable conductor

Abstract

The feasibility of high field magnet applications of the twisted stacked-tape cablingmethod with 2G YBCO tapes has been investigated. An analysis of torsional twiststrains of a thin HTS tape has been carried out taking into account the internalshortening compressive strains accompanied with the lengthening tensile strainsdue to the torsional twist. The model is benchmarked against experimental testsusing YBCO tapes. The critical current degradation and current distribution ofa four-tape conductor was evaluated by taking account of the twist strain, theself-field and the termination resistances. The critical current degradation for thetested YBCO cables can be explained by the perpendicular self-field effect. Itis shown that the critical current of a twisted stacked-tape conductor with afour-tape cable does not degrade with a twist pitch length as short as 120 mm.Current distribution among tapes and hysteresis losses are also investigated. Acompact joint termination method for a 2G YBCO tape cable has been developed.The twisted stacked-tape conductor method may be an attractive means for thefabrication of highly compact, high current cables from multiple flat HTS tapes.