Progress in the manufacturing of the 2nd generation of electrical conductors based on high-temperature superconducting (HTS) compounds, commonly known as coated conductors (CC), has sparked interest in various fields of application, including large magnetic systems for nuclear fusion and particle accelerators. To achieve the required electrical transport capacity in the kA range, tens of tapes must be assembled into a cable. Then, knowing the vulnerability of individual tapes to mechanical deformation is essential. We studied the behaviour of filamentized CC tapes with REBCO layer deposited on patterned substrate. Before this study, it was not clear whether such superconductor filamentization would affect the minimum core diameter, D c,min , at which it still retains the transport capability. In the first stage, a set of 12 mm wide research samples, prepared with various number of filaments, underwent off-axis bending tests. Microstructural investigation then enabled understanding of the observed fact that the filamentary architecture did not cause any visible loss of transporting capability. In the study continuation, we compared the off-axis bending performance of short samples taken from 4 mm wide tapes produced industrially in lengths exceeding 100 m. Encouragingly, these filamentized tapes exhibited an endurance comparable to that of an equivalent non-filamentized tapes. Finally, in the last part of the study, simple models of round cables containing longer pieces (30 cm) of filamentized tape wrapped around a round core were tested. Some deterioration of performance was observed, relative to previous tests when only ∼1 cm long portion of tape was affected. Nevertheless, the observed 100 % retention of critical current when bending the 4 mm wide filamentized tape on a 5.5 mm central core represents an important input to further discussion about adopting filamentized tapes, thanks to their better electromagnetic behaviour, in cables for future nuclear fusion reactors and particle accelerator magnets.
Ries et al. (Tue,) studied this question.