TORSION STRAIN EFFECTS ON CRITICAL CURRENTS
OF HTS SUPERCONDUCTING TAPES

Makoto Takayasu, Joseph V. Minervini, and Leslie Bromberg

Massachusetts Institute of Technology
Plasma Science and Fusion Center Cambridge MA, 02139, USA

ABSTRACT - A torsional twist strain effect on the critical current of a thin HTS tape has been found to be well described by a longitudinal strain model taking into account the internal shortening compressive strains accompanied with the tensile longitudinal strains due to a torsional twist. The critical current of a twisted tape is given by the integration of the critical current densities corresponding to the strain distribution over the tape cross-section using axial strain data of the tape. The model is supported with experimental results of YBCO and BSCCO-2223 tapes. It has been also found that torsional twisting effects on the critical currents of a tape composing of the conventional lapped-tape cable and the twisted stacked-tape cable are described by the same equation as that of a twisted single tape.

KEYWORDS: Torsion, twist, cabling, tape cable, critical current, high temperature superconductor, HTS cable

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IEEE/CSC & ESAS EUROPEAN SUPERCONDUCTIVITY NEWS FORUM (ESNF), No. 10, October 2009
On June 29, 2009, this manuscript was submitted for possible publication in “Advances of Cryogenic Engineering (Materials)”