A Gourd-Shape Architecture of HTS Coil With Functions of Flux Density Amplification and Flux Accumulation

This paper presents a gourd-shape closed loop with double circular configurations at different diameters, which is arranged by slitting second-generation high-temperature superconducting (2G HTS) tape along its length direction. The flux density amplification and flux accumulation mechanisms of this architecture with closed-loop HTS coils using both experimental and numerical methods were performed. Flux density amplification and flux accumulation in small circular configuration was observed by using field-cooling (FC) method in LN2 temperature. The mechanisms of flux density amplification and flux accumulation can be understood by the flux conservation law in superconducting closed loop. Three types of arrangements were carried out to confirm the principles of flux density amplification and flux accumulation. Compared with existing HTS magnetic magnets by winding on former, this gourd-shape HTS coil is more compact and operates in persistent current mode (PCM). Besides, it can be particularly generalized to big dimensional size permanent HTS magnet by stacking gourd coils if 2G tape with large width can be prepared for industrial application. Our results show that the proposed gourd-shape HTS coil is very promising in full HTS magnet with higher magnetic field in low temperature and has the potential to provide much stronger magnetic fields relative to existing permanent magnets.