Yuri Igitkhanov

Modeling of DEMO PFC Erosion Due to ELM Impact

The transient events could pose a severe tread causing a melting and erosion of plasma-facing components in the fusion power plant DEMO. Here we analyze the impact of the edge-localized modes (ELMs) on the divertor target and the first wall (FW) surface. The expected ELMs characteristics in DEMO are derived by extrapolating predictions made for ITER and using the scaling arguments found from existing experiments. The tungsten armor damage and effect of melt layer motion owing to the repetitive ELM loads are numerically investigated. The detailed description of the model for simulation of the melt motion (used in the melt motion at surfaces code) is described. It is shown that due to the unmitigated repetitive ELM impact, the divertor plate melts whereas FW does not. The divertor surface of monoblock W divertor module with water coolant tolerates the mitigated ELMs with 33 times (like in ITER) does not melt even in the case of advanced version of DEMO loads.

Effect of the Dome on the Collisional Neutral Gas Flow in the Demo Divertor

This paper presents the analyses of the dome effect on the pumping efficiency and screening of the neutrals for the European DEMO ITER-like divertor configuration of 2015. The effect of the dome on neutral compression in the private flux region is assessed by using the DIVGAS code based on the direct simulation Monte Carlo method. The numerical analysis includes the calculation of neutral density, temperature, and pressure in the divertor plenum and the overall conductance of the subdivertor structure, which consequently affects the estimation of the effective pumping speed. It is quantified how the presence of the dome impedes the reflux of neutrals toward the plasma. In addition, due to the intermolecular interactions, the dome does not strongly influence the macroscopic quantities near the pumping duct. A strong reflux of neutrals in the domeless case, as it was previously found in the free molecular flow case, is confirmed to be present also in the case of a collisional flow.

Erosion of PFC in DEMO due to ELM impact

The transient events could pose a severe tread causing a melting and erosion of plasma facing components in the fusion power plant DEMO. Here we analyze the impact of the edge localized modes (ELMs) on the divertor target and the first wall surface. The expected ELMs characteristics in DEMO are derived by extrapolating predictions made for ITER and by using the scaling arguments found from existing experiments. The tungsten armor damage and effect of melt layer motion due to the repetitive ELM loads is numerically investigated by using the MEMOS code (Bazylev, 2002). It is shown that due to the ELMs repetitive impact the divertor plate melts and the total tungsten surface roughness on the divertor plate considerably grows. The ELMs heat impact on the DEMO first wall does not cause melting of the W armor. It is proven that for controlled (like in ITER) ELMs a pure W divertor module with water coolant tolerates energy loads even in the case of advanced version of DEMO.