Extreme ultraviolet spectrometers for fast observation of high-Z impurity line emissions and their radial profiles in the Experimental Advanced Superconducting Tokamak

Abstract In the Experimental Advanced Superconducting Tokamak (EAST), eight sets of extreme ultraviolet spectrometers have been developed to observe the temporal behavior and spatial distribution of impurity ions in the plasma, enabling the study of impurity transport and their impact on plasma performance. Four sets of fast-time-responseextreme ultraviolet (EUV) spectrometers, working at 5–500 Å, are capable of a temporal resolution of 5 ms/frame and are employed to study the time behavior of multiple charge stages from all the impurity species in EAST plasma. Two sets of space-resolved EUV spectrometers working at 30–520 Å and covering a large viewing range of ΔZ = 90 cm (at R = 1.9 m, ρ ≤ 0.7), and another two sets of space-resolved spectrometers, working at 5–138 Å with high temporal resolution of up to 15 ms/frame, are used to observe the spatiotemporal evolution of medium- and high-Z ions in the bulk plasma. As a result, the behavior of copper ions observed during the impurity burst phase in long-pulse discharges using these EUV spectrometers are presented, which demonstrates the excellent performance and the stability of the EUV spectrometers in long-pulse discharges. Experimental and modeling study on impurity transport is being carried out using the informative data provided by the high-performance EUV spectrometers.