Study of Temperature and Heat Flux on the EAST Divertor Target Plate in LHW+ NBI/ICRH H-Mode

Abstract

The heat fluxes on the lower outer divertor plate were calculated using the DFLUX code with the surface temperature measured by the IR camera on the experimental advanced superconducting tokamak. The analyzed discharges were lower single-null divertor configuration discharges with different auxiliary heating: lower hybrid wave current drive (LHCD) combined with neutral beam injection (NBI) and LHCD combined with ion cyclotron resonant heating (ICRH). The surface temperature of the lower outer divertor target plate was about 170 °C in the LHCD + NBI H-mode, with the high temperature mostly distributed in the location near the joint of the dome and the outer target plate. The temperature increased as the NBI was turned on and fluctuated due to edge localized modes (ELMs). The heat flux reached nearly 4 MW/m2 when ELMs appeared and declined to less than 1 MW/m2 when the NBI was turned off. Temperature distribution with extreme toroidal asymmetry was observed in the selected LHCD + ICRH H-mode discharge. The surface temperature on the lower outer divertor target plate was up to 220 °C in one region with broader temperature distribution. During the LHCD + ICRH H-mode, the peak heat flux was not seen during the period of ICRH injection, though a brief spike in heat flux was observed at the beginning of the ICRH injection. The full-width at half-maximum of the heat flux profile as a function of divertor target plate location of the LHCD + ICRH H-mode is three times that of the LHCD + NBI H-mode.