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The no-insulation (NI) winding method is widely known for its ability to improve the stability of high-temperature superconductor (HTS) coils by bypassing the hot spot during a local quench. However, one major drawback of this method is the occurrence of charge and discharge delays due to current leakage between winding turns. To address this limitation, we recently proposed an impregnation technique using an electrically-conductive epoxy composite. This approach has shown the potential to reduce the charge/discharge delay while maintaining the inherent quench protection of NI HTS coils. Following this study, this paper aims to evaluate the proposed impregnation technique in a racetrack HTS coil, which is widely used in applications such as superconducting motors and generators. This study involves the fabrication and performance testing of racetrack HTS coils impregnated with an electrically-conductive epoxy composite, focusing on key aspects such as charge/discharge behavior and over-current characteristics. The results validate the feasibility of this method for larger and more practical HTS coil geometries, as well as its applicability in HTS electrical machines and other industrial systems.
This work was supported by the National R&D Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Science and ICT under Grant 2022M3I9A1073187, and the National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIT) (No. RS-2024-00391886).
