Quench protection for high [formula omitted] superconducting rotating gantry model magnet with I-V characteristics measured in the temperature range of 40–83 K

Abstract

We studied quench protection criteria for high transition-temperature superconducting (HTS) model magnet that was fabricated to demonstrate the possibility of HTS-based gantry. We aim to evaluate the frequency of “flux jump” events of this model magnet with varying operating temperature (TOP), which was observed during previous excitation tests. Therefore, we investigated the operation margin for various TOPs based on simulation and developed the quench protection system of this model magnet. A short sample of rare-earth barium copper oxide coated conductor, which was used for winding the HTS coil, was prepared and its current-voltage characteristics were measured between the temperature range of 40–83 K. The obtained results were then implemented to our stand-alone simulation to perform the quench study. The maximum allowed elapsed time after the magnet quench was investigated for different operating currents and TOPs by varying the detection voltages (Vdets). Then, a protection circuit was integrated into our simulation to optimize the size of dump resistor (Rdump) and Vdet. Finally, it was observed that Rdump must not be above 4 Ω and Vdet must be kept below 50 mV to protect the HTS model magnet.