Variations in critical current density of TSSC cable under torsional and radial loads

Abstract

A 3D finite element mechanical-electric numerical model was constructed to analyze the mechanical-electric performance of TSSC cables under torsional and radial loads at 77 K. The results indicate that when subjected to torsional load, the tapes in the outermost region within the slot of TSSC cable initially exhibit a decreasing trend, gradually expanding towards the inner region. The magnitude of this decrease progressively diminishes in the direction from outer to inner. Conversely, under radial loading, the normalized critical current density of the tapes in the innermost region within the slot initially decreases and expands outward along the radius. The tapes in the middle region remain mostly unaltered, while the outer region follows a pattern of increasing from inside out and reaches its peak at layers 28 and 29. Moreover, under torsional loads, TSSC cables display a higher normalized critical current density in the counterclockwise direction compared to the clockwise direction. To enhance the critical current density performance of TSSC cables under torsional loads, it is suggested to appropriately reduce the pitch, decrease the width of superconducting tape, increase the number of stacked tapes, enlarge the width of the slot and the diameter of the diversion trench, as well as increase the inner diameter while decreasing the outer diameter of the helical core. The choice of material for helical cores is not significantly impactful. On the other hand, under radial loads, factors such as tape width, number of stacked tapes, slot width, diversion trench diameter, and inner and outer diameters of the helical core have similar effects. Additionally, increasing the pitch length or adding more slots can enhance the critical current density performance of TSSC cables. Selecting different materials for the helical core also contributes positively to this improvement.