Ic degradation behavior in Bi-2223 superconducting tapes under torsional deformation

In this study, the Ic degradation behavior in HTS tapes due to torsional deformation was investigated. Three kinds of commercially available Bi-2223 tapes were used. The sample holder for torsion test of HTS tapes was newly devised. Utilizing it, the influence of the torsion angle on the critical current (Ic) and n-value in Ag alloy/Bi-2223 tapes was investigated at 77 K. The Ic began to degrade when the torsion angle exceeded 150 deg. , after which, it showed a gradual decrease with an increase in torsion angle. Superconducting tapes with larger number of filaments showed more significant Ic degradation compared to tapes with smaller number of filaments. The n-value also showed a similar behavior to the Ic(θ) behavior. Eventually, it was found that the torsion strain did not significantly reduce the critical currents of Bi-2223 tapes, when compared with cases of other loading types such as bending or tension