Validation of ERMES 20.0 finite element code for MAST Upgrade O-X mode conversion

This study presents the validation of the frequency-domain finite element code ERMES 20.0, benchmarked against Finite Difference Time Domain (FDTD) solvers. The simulations focus on Ordinary–Extraordinary (O–X) mode conversion in the Electron Bernstein Wave (EBW) regime of the MAST Upgrade experiment. Validation is performed in terms of mode conversion efficiency and wave propagation characteristics. Several finite element formulations are tested and compared with the FDTD results. The simulations demonstrate excellent agreement between the different approaches, confirming the accuracy and robustness of ERMES 20.0 for modeling cold plasma wave interactions.