A high-speed vacuum ultraviolet (VUV) imaging system has been developed on the Experimental Advanced Superconducting Tokamak (EAST), which selectively measures line emission with a central wavelength of 13.5 nm (CVI, n = 4–2). It has been employed to study edge/pedestal plasma behavior in EAST. Edge localized mode (ELM)-induced filament structures have been captured by the VUV imaging system during the ELMy high confinement mode discharge with both high temporal and spatial resolutions. The typical features (i.e. poloidal width and pitch angle) of the observed filaments are quantitatively characterized based on the VUV imaging data, and the dependence of these features on basic plasma parameters is analyzed. It is found that the poloidal width is proportional to the heating power, and the pitch angle is inversely proportional to the edge safety factor q 95 . The scatterplot shows a positive trend between the poloidal width and the ELM amplitude defined by the relative change in stored energy. These results are based on the condition that the perturbation induced by ELMs is confined to a narrow layer in the plasma.

A calorimetry system has been developed in Experimental Advanced Superconducting Tokamak (EAST). It is employed to evaluate the heat load exhausted by cooling water. Full poloidal coverage is achieved after the upgrade in 2019. The experimental results show that the heat load exhausted by cooling water is 64% - 86% of the injected energy. Moreover, the heat load increases faster in the case with a higher heating power, and this is qualitatively confirmed by the simulation. In addition, a longer time is required for the temperature of the cooling water to achieve its maximum for a higher heating power. And in the decay phase of the water temperature, it shows an exponential characteristic. The averaged time constant of the thermal decay obtained by exponential fitting for the upper and the lower divertor are 12.1 s and 107.9 s, respectively. It indicates that the heat removal capability of the upper tungsten divertor outperforms the lower graphite divertor.

In type I ELMy H-mode experiment, Edge localized mode (ELM) filaments are clearly captured by the high-speed vacuum ultraviolet imaging (VUVI) system which is developed on the Experimental Advanced Superconducting Tokamak. To analyze the ELM filament structures, the so-called singular value decomposition is performed on the imaging data to extract the key fluctuating components. In this work, the filament structure is characterized by the pitch angle and poloidal width. In a single ELM crash, it is found that the poloidal width increases (decreases) in the rise (decay) phase of the VUVI intensity induced by ELM crash. The pitch angle derived from the VUVI data agrees well with that calculated by the Equilibrium FITting code, indicating the filaments are aligned with the field lines. The poloidal velocity shows no obvious change during the rise and decay phases in an ELM crash. In addition, both the poloidal width and the poloidal velocity of the filament increase with the heating power. Since the filament structures are extracted from the line-integrated imaging data, all these results are obtained on the condition that the ELMs are confined to a narrow layer in the plasma.