Performance Degradation of Multi-Layer Spiral Cable During Manufacturing Procedure

Multi-layer spiral compact cable based on Rare-Earth-Barium-Copper-Oxide (REBCO) high temperature superconducting (HTS) tapes is a potential candidate for large scale superconducting applications. The performance degradation caused by mechanical damage during cable processing has always been a concern. Accurate prediction of critical current is very important for functionality and safety of superconducting equipment. Mechanical simulation by finite element method (FEM) is considered a feasible method to predict strain and current properly due to the strain dependence of HTS tapes. In this paper, a spiral cable with 2 layers is selected as research object and its bending issue is focused. New simulation method is proposed, and the process of mechanical winding by reel-to-reel method is reproduced in finite element model. Two different simulation methods are compared about mechanical and electrical performance after bending and validation experiment are conducted. It was found that the critical current measured at 77K degrades heavily after cable bending in practical, which is far from the pure bending simulation results. Instead, the results of new reel-to-reel mode agree well with the tests and it is confirmed effective and necessary to replace the pure bending mode.