Multi-Sensor Quench Detection System for an HTS Slotted Superconducting Cable

Quench caused by electromechanical instabilities is a major concern in high-temperature superconducting (HTS) magnets, and quench detection methods, alternative to common voltage-based systems, are currently under study. In this work, we describe the experimental design and set-up, and we report the results of studies carried out on a cable equipped with bismuth strontium calcium copper oxide (BSCCO) tapes. The sample layout comprises an aluminum slotted core, cooled via a forced flow of liquid nitrogen in the central channel, and liquid nitrogen cooled termination. To trigger a quench in a well-defined position within the stack, a localized small magnetic field is employed to reduce the critical current density in the central zone of the cable. Various configuration of sensors including temperature sensors, voltage taps, and fiber Bragg grating (FBG) are installed, with the final aim of developing a fast and reliable quench detection set-up for the stacked-tapes HTS cable. It is shown that the response for both temperature and FBG signals are comparable for what concerns sensitivity and velocity, and both follow the voltage evolution in time. All in all, the developed setup with the multi-sensor allowed characterizing the electrical and thermal aspects of an HTS slotted-core superconducting cable during a localized magneto-thermal quench.