Trapped Field in Topological Stacked Gourd-Shaped HTS Loops Under Field-Cooling Magnetization

High-temperature superconducting (HTS) closed loop magnets composed of gourd-shaped RE–Ba–Cu–O (RE BCO, where RE denotes a rare earth element) plates show great potential for operating in the persistent-current mode (PCM), enabling magnetic-flux amplification and accumulation under field-cooling magnetization. Preliminary experiments and simulations have demonstrated that this configuration can trap substantial magnetic fields, with prospects exceeding 20 T in PCM operation. However, partial inductive coupling—arising from self- and mutual-inductance interactions between adjacent superconducting loops—can alter the induced current distribution and magnetic-flux density, thereby affecting overall flux amplification. In this study, experimental measurements combined with finite-element numerical modeling were performed to elucidate the mechanism of partial inductive coupling and quantify its influence on trapped-field magnitude and temporal stability. Furthermore, the concept was extended to HTS magnets comprising a larger number of REBCO plates, whose enhanced trapped-field performance was validated experimentally and numerically. These results provide a foundation for optimizing excitation strategies and stacking configurations in REBCO based HTS closed-loop magnets, advancing the development of robust and scalable high-field superconducting systems for persistent-current operation.