(FT/P2-11) Study of Radiation-Damaged Fusion Materials under High-Power Plasma Stream

V.S. Koidan1), A.N. Bryukhanov, O.K. Chugunov, V.M. Gureev, B.I. Khripunov, S.N. Kornienko, B.V. Kuteev, S.T. Latushkin, A.M. Muksunov, V.B. Petrov, A.I. Ryazanov, E.V. Semenov, V.P. Smirnov, V.G. Stolyarova, V.N. Unezhev
1) RRC Kurchatov Institute, Moscow, Russian Federation

Abstract.  Plasma-facing materials (PFM's) of a fusion reactor will be affected by high heat flux, fast particles and 14 MeV-neutron irradiation. All these factors are crucial for the lifetime of the reactor components. Fast neutrons produce a high level of radiation damage in materials during long operation of the fusion reactor (estimated value is up to hundred dpa). At the same time, PFM's will suffer from erosion induced by the plasma. While important data on the plasma erosion have been collected for non-irradiated materials, it is difficult to qualify PFM's at present taking into account radiation damage effect. This paper is devoted to the experimental results on radiation damage effect on erosion of materials under plasma impact. To obtain a high level of radiation damage, we simulated neutron irradiation by fast ions with energies of 1 - 60 MeV accelerated on the cyclotron at Kurchatov Institute. Using this method we can accumulate the radiation damage equivalent to fast neutron effect at the dose of up to 1026 neutron/m2 in a few days operation of the cyclotron. Both carbon materials and tungsten were taken for the study as the targets: MPG-8 (Russian graphite), SEP NB-31 (ITER PFM candidate) and W (99.95% wt). Irradiation of these materials on the cyclotron has been performed with 5 MeV carbon ions (for carbon materials) and alpha particles 3.4 MeV for tungsten. The experiments have been performed on the materials having accumulated 0.1 - 10 dpa of radiation damage. Plasma erosion was studied on the linear plasma simulator LENTA. Irradiated samples were exposed to steady-state deuterium plasma at 100 eV (deuterium ions) to dose of up to 1025 ion/m2. The microstructure modification was observed and comparison was made of damaged and non-irradiated materials. Enhancement of the erosion process was detected for the radiation-damaged materials. New experimental approach developed in this work to explore the plasma-facing materials for accounting of neutron effect and the results obtained appear to be important for the further studies of the combined plasma and neutron effect on fusion PFM's .

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