3D electromagnetic simulation of the coupling characteristics and double-stub Ferrite tuners impedance matching for EAST ICRH four-strap antenna

A program developed with COMSOL software integrates EAST four-strap antenna coupling with the double-stub Ferrite tuners (FT) impedance matching, obtaining physical quantities crucial for predicting the overall performance of the ion cyclotron resonance heating (ICRH) antenna and matching system. These quantities encompass S-matrix, port complex impedance, reflection coefficients, electric field and voltage distribution, and optimal matching settings. In this study, we explore the relationship between S-matrix, reflection coefficients, port complex impedance, and frequency. Then, we analyze the impact of Faraday screens placement position and transparency, the distance from the Faraday screen (FS) to the current straps (CS), the relative distance between ports, and the characteristic impedance of the transmission line on the coupling characteristic impedance of the EAST ICRH system. Finally, we simulate the electric field distribution and voltage distribution of the EAST ICRH system for plasma heating with double-stub FT impedance matching. Using optimized parameters, the coupling power of the ICRH system can be approximately doubled. The results present herein may offer guidance for the design of high-power, long-pulse operation ICRH antenna systems.