Numerical Investigation of AC Losses in Toroidal Full-Superconducting Resonator Using ReBCO Tapes

High-temperature superconducting (HTS) tapes exhibit a flat plate structure. Experiments have shown the characteristics of pancake-type superconducting capacitor using HTS tapes as electrodes. This pancake-type HTS capacitor also functions as an inductance because it creates a self-magnetic field, and the inductance and capacitance facilitate the creation of an all-superconducting resonant circuit by itself. As AC loss in the HTS circuit is converted into a resistive component, it exerts a significant impact on the Q-factor characteristic, which is the evaluation standard for resonant circuits. Thus, evaluating AC loss characteristics is very important for designing fully superconducting resonant circuits. In this study, the current distribution is not uniform towing to the charge transfer between electrodes in the toroidal full-superconducting resonator; thus, the AC loss was derived in each part using the finite element method (FEM). FEM was employed to derive the AC loss and Q-factor. Considering the resistance component that exists due to the AC losses being nonlinear with respect to the current, a simple equivalent circuit was used to derive the Q-factor.