Development of D_α band symmetrical visible optical diagnostic for boundary reconstruction on EAST tokamak

Abstract

To investigate the potential of utilizing visible spectral imaging for controlling the plasma boundary shape during stable operation of plasma in future Tokamak, a Dα band symmetric visible light diagnostic system was designed and implemented on the Experimental Advanced Superconducting Tokamak. This system leverages two symmetric optics for joint plasma imaging. The optical system exhibits a spatial resolution less than 2 mm at the poloidal cross-section, distortion within the field of view below 10%, and relative illumination of 91%. The high-quality images obtained enable clear observation of both the plasma boundary position and the characteristics of components within the vacuum vessel. Following system calibration and coordinate transformation, the image coordinate boundary features are mapped to the Tokamak coordinate system. Utilizing this system, the plasma boundary was reconstructed, and the resulting representation showed alignment with the EFIT results. This underscores the system’s superior performance in boundary reconstruction applications and provides a diagnostic foundation for boundary shape control based on visible spectral imaging.

Novel identification algorithm for plasma boundary gap based on visible endoscope diagnostic on EAST tokamak

“…The neutral particles in the outer regions of the tokamak plasma (e.g. neutral deuterium, carbon, lithium, and molybdenum atoms) were excited by the collisions with the energetic particles in the plasma upon reaching the plasma boundary [5][6][7]. They then decayed to emit light within the visible range.…”