Optical plasma boundary reconstruction using visible image on EAST Tokamak

Visible cameras are routinely used for monitoring of plasma discharges on Tokamak. According to experimental observation, tangentially viewed images of plasma from high-speed cameras are regarded as potential data which could be used to reconstruct the plasma boundary. The visible imaging system has been installed and calibrated for optical boundary reconstruction on the Experimental Advanced Superconducting Tokamak (EAST) in 2018 experiment campaign. Exploiting the plasma's edge localized and toroidally symmetric emission profile, plasma boundaries were reconstructed from the detected image edge features. The results were compared with magnetic boundaries from the reconstruction code EFIT, showing good agreement in the area near mid-plane. The processing time from image to optical boundary is less than 1 millisecond with general desktop computer and this method is promising to be used for plasma control.