Simultaneous reduction of tungsten and rotation in the core region induced by RMP

Tungsten (W) impurity control is critical for plasma performance and a priority for ITER. The simultaneous reduction of W and rotation in the core region induced by resonant magnetic perturbations (RMPs) has been found and understood in EAST. A positive feedback loop between the W and rotation is first proposed, resulting in core W accumulation and high rotation even in low-torque plasma before the RMP application. This cycle can be reversed by the edge rotation braking induced by RMP, causing a significant simultaneous reduction of W concentration and rotation. These new mechanisms are based on several repeatable experiments and confirmed by the modeling results from TGYRO and NTVTOK. It provides a new understanding of the RMP effects on W and rotation and can be used for W and rotation control in future reactors.