DC and quench performance assessment from the EUROfusion HTS Quench Experiment campaign and projection to magnet operation

Seven different high current conductors for fusion applications, made of High Temperature Superconducting stacked tapes, have been successfully tested in the Quench Experiment campaign supported by EUROfusion and carried out in SULTAN. The aim of this extensive experimental campaign is to explore the quench initiation and propagation in different conditions as well as different conductor design. The measurements show that there is a common behaviour to all layouts, i.e., the DC performance of such conductors have degraded after the quench test campaign, and more systematic DC experiments showed that it is likely that a temperature peak beyond 150 K on the stack may lead to the degradation. These results are analyzed and discussed in the present work. This allowed identifying a reference threshold for the safe operation in a real magnet. Through a simple analytical model, based on the assumption of adiabatic quench propagation, the projection to the expected performance in the magnet configuration is carried out, focusing on the maximum hotspot temperature reached, depending on the layout. It is shown that conductors with a larger effective heat capacity, although having a smaller quench propagation velocity, end up having lower hotspot temperature.