FEATURES OF MODIFICATIONS IN THE RE-SOLIDIFIED SURFACES OF ADVANCED MATERIALS DUE TO HIGH-POWER PLASMA PULSES

The surface modification of advanced materials was studied through a series of repetitive plasma pulses caused tungsten melting. Features of the affected surface layers in reference materials (IGP W, AM W/WTa, Hastelloy, and EUROFER) for both fusion and fission applications were explored after exposure to plasma in the facilities (QSPA, MPC, and PPA) with different durations of plasma pulses. A detailed surface analysis was carried out with Scanning Electron Microscopy. It was found that the plasma treatment led to the formation of a modified layer as a result of the rapid re-solidification of the exposed surface. The fine cellular structures appeared in the re-solidified layers of the irradiated materials, with typical cell sizes ranging from 150 to 500 nm. An increase in the roughness of the exposed surfaces was attributed to the presence of the cracks and re-solidified layer.