Impact of Deuterium Plasma Flux on Fusion Reactor Materials: Radiation Damage, Surface Modification, Erosion

Abstract

Results of the complex experimental research of plasma impact on fusion reactor materials are presented. The near-wall plasma of a tokamak reactor is simulated on the linear plasma device LENTA (National Research Center Kurchatov Institute). Plasma fluence of 10²²–10²³ cm^–2 to the material surface is provided at 10¹²–10¹³ cm^–3 of plasma density in steady-state operation of the device, thus simulating the continuous regime of the fusion reactor plasma-wall conditions. The neutron effect on the first wall material (radiation damage) is also simulated by irradiation with high-energy ions accelerated by a cyclotron to MeV-range energies. The work is centered mainly on tungsten being a candidate for coating of the divertor region in the tokamak reactor. Samples irradiated at doses of 10²¹–10²³ ion/cm² to a high damage level from 0.1 to 80–100 displacements per atom characteristic of a durable operation of the reactor have been obtained on the cyclotron at the National Research Center Kurchatov Institute. Helium, carbon, and nitrogen ions and protons whose defect generation mechanisms are very different have been used in irradiations. Erosion data (erosion rate, erosion yield), swelling characteristics (profilometry), and microstructure changes (SEM) of the damaged surface layer are given for tungsten preirradiated with fast nitrogen ions. Proton-irradiated silicon carbide SiC has also been studied in deuterium plasma, and changes in its microstructure are found.