Degradation of Critical Current in an HTS Tape With Combined Bending and Torsion Considering Curvature of Elliptical Shape

Degradation of critical current (I
_c
) in a high-temperature superconducting (HTS) tape under bending conditions had been previously investigated. These investigations were focused on only either bending or torsion. A rotating flux pump is used to study the charging characteristics of an HTS synchronous motor. In order to design the rotating flux pump connected in series, the elliptical winding applied together with combined bending and torsion is essential. Therefore, in this paper, the critical current considering curvature of elliptical shape is measured with regard to nine kinds of mandrels. The shapes of the mandrels are a tall prolate ellipsoid, oblate ellipsoid, and semicircle. The diameters of each shape are 20, 30, and 40 mm, respectively. The experiments are mainly composed of three conditions: straight, bending, and combined bending and torsion. Finally, the experimental observations have been compared with the theoretical predictions.