Experimental investigation of ICRF-edge plasma interactions and surface wave excitation during ICRF heating on EAST

Although ion cyclotron resonance heating plasma has succeeded in tokamaks, it also faces the problem of wave-related impurities, especially in the future operation environment with an all-metal first wall. By controlling the antenna wave spectrum, we experimentally observed the behavior of impurities and the radial electric field on the Experimental Advanced Superconducting Tokamak (EAST) and used the finite element code to calculate the wave propagation and the dissipation behavior at the plasma edge. The results demonstrate that the radial electric field is relatively high in the region with a steep density gradient, and the electric field in the monopole phase is higher than in other phases. Although particular electric field strength was observed in the low hybrid resonance region, the electric field was not as high as theoretically predicted. This evidence is more inclined to support the view that a steep gradient leads to the generation of surface waves by the waves, which enhances the interaction between the waves and the first wall and thus increases impurities.