Influence of rhenium addition on deuterium plasma-driven permeation and retention in tungsten coatings

The effect of transmutation element rhenium (Re) on deuterium (D) plasma-driven permeation (PDP) and retention in magnetron-sputtered W coatings was studied. It was found that the W-Re coating showed higher steady-state D permeation flux and diffusion coefficient than the pure W coating, which was attributed to the influence of Re on the capture energy of D in W. The TDS results showed that W-Re coating had lower D retention compared to pure W coating. The decreased D inventory was due to the higher solvation energy of D in W-Re coatings and the repulsive effect of Re on D atoms. The impact of W-Re coatings thickness on D permeation was also investigated. D-PDP flux and the effective diffusion coefficient were found to decrease as the coating thickness increased. The study examined the impact of incident ion energy on D-PDP. The presence of coatings altered the balance between bulk diffusion and surface recombination dynamics. Besides, He pre-irradiation of W and W-Re coatings revealed that He irradiation reduced the D-PDP flux and increased the D diffusion coefficient in the coatings due to the formation of He bubbles. The diffusion coefficient of irradiated W-Re coating was lower than that of irradiated pure W coating because the Re element of the W-Re coating stabilized the crystal lattice structure.