Numerical study of the erosion of the EAST tungsten divertor targets caused by edge localized modes

Abstract

Edge localized modes (ELMs) in company with high-confinement mode (H-mode) will release high energy plasma fluxes to the scrape of layer (SOL). Large portions of these high heat fluxes will eventually irradiate the divertor target plates, and may erode, even melt them. In this paper, we develope a one-dimensional heat conductivity model including evaporation, radiation, melting processes of tungsten to study the erosion of the divertor tungsten targets caused by ELMs in EAST at the current and possible future operation parameters. Based on both experimental data of heat fluxes on the carbon-fibre composites divertor in EAST and possible future data of high heat fluxes, the surface temperature of slab-shaped tungsten is evaluated numerically by solving the one-dimensional model. It is found that the current Type I ELMs do not cause any noticeable changes of the tungsten target, the surface temperature being raised only several tens of degrees. Simulation results show that ELMs will not become a problem for EAST tungsten wall for the time being and the near future as long as much more severe transient events, e.g., disruption, can be avoided. When deposition energy is increased to 1 MJ/m2 with a duration of 600 μs, the tungsten plate will melt for a layer as thick as 6.8 μm.