Experimental demonstration of RF-induced particle flux reduction using a toroidally localized electrode in a divertor-leg-like plasma

Radio-frequency (RF) modification of edge plasma transport provides a potential pathway for active control of particle and heat fluxes in magnetically confined plasmas. In this study, we experimentally demonstrate RF-induced transport modification in a toroidal open-field-line plasma produced in QUEST, using a toroidally localized electrode to generate transverse RF electric fields in a divertor-leg-like region. Application of RF fields with amplitudes of approximately 100 V cm (Formula presented) (Formula presented) results in a significant reduction in particle flux to the divertor target, achieving up to a 25% decrease in the total flux. The flux reduction rate is found to scale with the square of the applied RF electric field, consistent with the formation of an effective ponderomotive potential. Quantitative agreement with an analytical model further indicates that RF-induced modification of the parallel force balance plays a dominant role in the observed transport changes. These results demonstrate that RF-induced forces can provide a dynamically tunable mechanism for controlling parallel transport and mitigating divertor particle fluxes, thereby establishing RF-based transport control as an actively tunable approach and a promising concept for next-generation divertor systems in future fusion devices.