Numerical and Experimental Design of the Former for TORT Cables

TORT (Tapes on Round Tube) cables, which implement high-temperature superconducting (HTS) tapes, offer additional benefit over other HTS cables, which is the internal cooling in the former itself. Up to now, the superconducting tapes of existing TORT cables have been wound on a copper tube of various diameters. However, in the alternating current (AC) mode, the high conductivity of the former causes undesirable eddy currents. Therefore, it is necessary to replace the copper with a less electrically conductive material. We designed a former from polyethylene terephthalate glycol-modified and reinforced with carbon fibers (PETG CF), polycarbonate (PC) and polycarbonate reinforced with carbon fibers (PC CF) materials in order to reduce the AC losses in TORT cables, using 3D printing technology. Because of the low thermal conductivity of polymers, the former must be specially designed to improve the cooling of the HTS tapes inside the former. Moreover, thermal deformation of the former during cooling from room temperature to liquid nitrogen temperature and resilience against low-diameter bending is another important issue that was taken into account. Detailed structural finite-element (FE) analysis was carried out using the FE modeling software ANSYS, in prototyping of the former. Based on the numerical models, formers differing in the materials used were fabricated, and subsequently a short TORT cable with wound HTS tape was electromagnetically characterized.