Deuterium and helium retention in tungsten based materials exposed to plasma

5^th World Congress on Physics

July 17-18, 2018 Prague, Czech Republic

O V Ogorodnikova

National Research Nuclear University MEPhI, Russia

Posters & Accepted Abstracts: J Laser Opt Photonics

Abstract :

Tungsten and dense nano-structured tungsten (W) coatings are used as plasma-facing materials in current tokamaks and [A1] suggested to be used also for the future fusion devices, ITER and DEMO. In the fusion reactor, W will be exposed to energetic particles of hydrogen isotopes and helium (He), high heat flux and neutrons. In this regard, a study of accumulation of deuterium (D) and He in W under normal operation conditions and transit events is necessary for assessment of safety of fusion reactor due to the radioactivity of tritium and material performance and for the plasma fuel balance. Therefore, W samples were exposed to lowtemperature plasma to simulate normal operation regimes and pulsed heat loads using D plasma in quasi-stationary high-current plasma gun QSPA-T to simulate transit events. We found that D and He concentrations increased with decreasing the grain size. The D retention was the highest for samples irradiated by plasma gun above the melting threshold. The D retention after 10 pulses of plasma gun exposure was much higher than that after stationary low-energy plasma exposure at sample temperature of either 600 K or 700 K indicating the dominating influence of ELM’s-like events on the D retention compared to normal operation regime. The D retention in W samples with the presence of He-induced W fuzz was smaller than without that. The results obtained gives possibility to assess the particle retention in diverter areas subjected to high thermal loads at different operation regimes.

Biography :

E-mail: olga@plasma.mephi.ru