Synthetic diagnostic for electron cyclotron emission imaging

Synthetic diagnostics are aimed at simulating the response of diagnostic systems under actual experimental scenarios and are the key to drawing quantitative inferences from experimental data. The synthetic Electron Cyclotron Emission Imaging (ECEI) diagnostic is suitable for evaluation of the improvement arising from the application of Field Curvature Adjustment (FCA) lenses in the design of the upgraded Experimental Advanced Superconducting Tokamak (EAST) tokamak ECEI system. In previous ECEI systems, a curved image plane is inevitable in optics systems comprising only convex lenses, which leads to significant crosstalk between vertically adjacent channels and strongly limits the vertical channel resolution of the imaging system. The synthetic ECEI diagnostic results show that, with FCA lenses applied, the upgraded ECEI system has significant advantages to focus on high poloidal wavenumber structures with the aberrations from the spherical surfaces corrected and the various artifacts related to the field curvature suppressed. Also, the synthetic ECEI diagnostic is used for some quantitative calculations to partially decouple the effect of density fluctuations and temperature fluctuations for a given plasma.