Simulation of iter transient heat loads to the divertor surfaces with using the powerful quasi-steady-state plasma accelerator

Abstract

The results of experiments on powerful plasma stream -surface interaction in conditions of heat loads typical for current disruptions in reactor-tokamak ITER are presented here. The long pulse powerful plasma streams are generated with quasi-steady-state plasma accelerator QSPA Kh-50. The morphology of surfaces of tungsten and graphite, as well as surface of combined tungsten-graphite targets exposed to powerful plasma streams is analyzed. Some erosion properties of these materials are presented and compared with results of numerical simulations.PACS : 52.40.Hf

Principal physics developments evaluated in the ITER design review

“…Recent analyses by the ITPA of divertor heat loads due to ELMs indicate that the peak heat loads are projected to be greater since the heat fluxes are more localized relative to the analysis in the Progress in the ITER Physics Basis [29]. In addition, new information about material damage for both carbon fibre composite and tungsten divertor targets has become available as shown in figure 16 [51,52]. The conclusion is that an incident energy impulse of more than ∼0.3% of the total thermal plasma energy (∼1 MJ) can cause tile fatigue and cracking as well as erosion, and larger energy losses can ablate or melt divertor materials, potentially degrading the purity of ITER plasmas and greatly reducing the lifetime of the ITER divertor.…”

Edge localized mode control experiments on MAST using resonant magnetic perturbations from in-vessel coils

“…This has been identified as a critical threat to the lifetime of the plasma facing components (PFCs), in particular the divertor. The maximal tolerable ELM size for the divertor materials (whether tungsten or carbon fibres) not to be damaged is considered to be ∼1 MJ, based on the result of plasma gun experiments [5]. ELMs therefore have to be reduced by at least a factor of 20 in ITER.…”

22nd IAEA Fusion Energy Conference: summary of contributions on Fusion Technology and ITER Activities

“…As the 15 MA reference discharge is predicted to have ∼100 MJ in the pedestal, values of up to 20 MJ can be expected if ELMs are not mitigated. Several aspects of the ELM damage and mitigation studies for ITER were presented: the physics specification for the ELM loads on PFC and divertor were summarized from present multimachine studies [25]; the overall strategy for mitigating ELMs on ITER [26]; experimental measurements simulating ELM damage in a plasma stream [27] and the developments in 'ELM-pacing' by pellets [28]. The multi-machine studies show that the energy density in an unmitigated ELM can reach ∼10 MJ m −2 at the target.…”