Development of Computational and Experimental Imaging Sensing System for Tokamak Plasma Optical Boundary Reconstruction

The precise determination of the last closed flux surface (LCFS) location holds paramount importance in fusion plasma discharge experiments. Traditional magnetic measurements, employing electromagnetic probe sensors, are widely utilized for LCFS detection but face accuracy challenges due to factors like neutron radiation and measurement drift. The optical measurement method, centered around imaging sensors, has been recognized as a practical and complementary solution, leading to the implementation of the high-speed image acquisition and processing system (HIAPs) on the experimental advanced superconducting tokamak (EAST) for real-time LCFS detection in plasma control. Efforts have been made to enhance LCFS detection accuracy by upgrading the HIAPs' imaging system. The optimization of the optical plasma boundary reconstruction imaging system began with a comprehensive theoretical analysis of computational imaging techniques applied to EAST discharge plasma. Computational imaging simulations of the plasma were subsequently conducted to fine-tune optics design parameters. Based on the insights gained from theoretical and simulation analyses, a novel optical system has been meticulously designed, developed, and integrated into the EAST experiment. Preliminary experimental results indicate that the upgraded HIAPs is capable of achieving optical plasma boundary reconstruction within a total time cost of approximately 110~\mu s, aligning seamlessly with the current plasma control requirements of the EAST experiment.