Full-wave simulations of frequency-modulated continuous-wave reflectometry perturbations induced by edge-localised mode filaments

Le résumé fourni par la source

Filamentary structures associated with edge-localised modes (ELMs) introduce strong localised density perturbations in the plasma edge, leading to non-trivial wave–plasma interactions that complicate the interpretation of frequency-modulated continuous-wave (FMCW) reflectometry measurements. Using two-dimensional full-wave simulations, we systematically investigate the propagation and reflection of microwave beams in the presence of ELM filaments, focusing on the effects of filament peak density, radial width and beam-axis displacement (poloidal offset). The simulations qualitatively reproduce the main frequency-hopping signature observed in EAST experiments and further show beam broadening, beam deflection and the formation of multiple effective reflection paths as characteristic signatures of filament–wave interaction. Parametric scans indicate that the reflection strength increases with filament density up to the cutoff condition, while filament width strongly influences the reflected response. By contrast, beam-axis displacement mainly alters the symmetry of the reflecting field and has a comparatively weak influence on the hopping amplitude. In the present model, the intermediate-frequency (IF) hopping interval is found to be more sensitive to filament width than to filament displacement, suggesting a simulation-based sensitivity of IF hopping to the effective radial scale of filamentary perturbations under the present reduced-model assumptions. Quantitative experimental validation, however, remains for future work. These results show that FMCW reflectometry is sensitive not only to the background density profile but also to filamentary structures, supporting its potential as a diagnostic of edge perturbations in reactor-relevant devices such as ITER.

Ce résumé expose les affirmations des auteurs. BNTIC ne l’interprète pas comme une validation indépendante des résultats.