Comprehensive modeling of ELMs and their effect on plasma-facing surfaces during normal tokamak operation

During the normal operation of the high confinement regime (H-mode) in next generation tokamaks, edge-localized modes (ELMs) are a serious concern for divertor plasma-facing components. The periodic relaxation of edge pressure gradient results in pulses of energy and particles transported across the Separatrix to the scrape-off-layer (SOL) and eventually to the divertor surface. ELMs could, therefore, result in cyclic thermal stresses, excessive target erosion, and consequently shorter divertor lifetime. In this study a comprehensive two-fluid model has been developed to integrate SOL parameters during ELMs with divertor surface evolution (melting, vaporization, vapor cloud dynamics, and macroscopic spallation) for different ELM parameters. Calculations were performed using the HEIGHTS numerical simulation package. Initial results indicate that high-power ELMs in ITER-like machines can cause serious damage to divertor components, may terminate plasma in disruptions, and may affect subsequent plasma operations due to extensive contamination.