Temperature Distribution and Heat Flux on the EAST Divertor Targets in H-Mode

An infrared camera (IR) has been put into operation in the Experimental Advanced Superconducting Tokamak (EAST), which is used to measure the temperature distribution on the surface of lower divertor target plates. With a finite difference method, the heat flux onto the divertor target plates is calculated from the surface temperature profile. The high confinement mode (H-mode) with type-III edge localized modes (ELMs) has been obtained with about 1 MW lower-hybrid wave power on the EAST in the autumn experiment in 2010. The analyzed H-mode discharges were lower single null X-point diverted discharges with a density range of < ne > (1 ∼ 4) × 1019 m−3. The surface temperature of the inner target plate increases with heating power. The peak temperature on the surface of target plates is lower than 200°C with about 2.4 MW heating power. Comparison among the heat flux profiles occurring in different phases in the same discharge has been performed. It indicates that the heat flux profile obviously changes from the ohmic phase to the H-mode phase, and the full width at half maximum (FWHM) of the heat flux profile is the narrowest during the ELM-free H-phase. On the outer target plate, the peak heat flux exceeds 2 MW/m2 during the ELMy H-mode phase, whereas it is only about 0.8 MW/m2 during the ELM-free phase in the same discharge.