Investigation of current and temperature distribution during quench in YBCO CC: direct observation and numerical simulation

Abstract For YBa 2 Cu 3 O 7− δ (YBCO) coated conductors (CCs) carrying high currents at low temperature, the quenching process typically starts with a local hot spot, which then propagates through the tape. A better understanding of the local quench evolution is essential for ensuring the stable operation of superconducting devices. In this paper, we combined full temperature field measurements with numerical simulations based on the finite element method (FEM) to study the thermal and current distributions around the quenched regions. First, the full temperature field during the quenching process was measured using fluorescent thermal imaging, revealing that the quench region initially spreads transversely before propagating longitudinally, with faster propagation at the tape edges. Furthermore, by analyzing the temperature rise curves in characteristic regions, we observed that the energy required to trigger irreversible quench differs depending on the initial hotspot location, and the temperature evolution also varies across different hotspots. Finally, a three-dimensional FEM model of the YBCO CC was developed, coupling the H -formulation with the heat conduction equation to replicate the thermal distribution observed in experiments. The current distribution in the superconducting and stabilizer layers during a quench was also calculated, showing that a local hotspot forces the current to flow around it in the superconducting layer, which then diverts to the stabilizer layer, generating Joule heat that further increases the temperature.