Trapping Of Permeating Deuterium In Defect Induced At The Rear Side Of Tungsten Samples

As plasma-facing material in the Iter divertor area, tungsten will be subjected to bombardment with low-energy, high-flux deuterium and tritium particles, as well as 14 MeV neutrons. At elevated temperatures, hydrogen isotopes can diffuse into W material and can be trapped in n-induced defects. To account for this effect, the trapping of diffusing deuterium at defects generated in the rear side of the 25 and 500 mu m thick W samples damaged up to a depth of 2.2 mu m to a damage level of similar to 0.3 dpa was studied. The front side of each sample was exposed to a deuterium plasma at elevated temperatures. The results show that D atoms permeate through the whole width of the sample and are trapped in ion-induced defects. The highest D retention was measured at 460 K - beyond that point, due to the de-trapping process, it decreases with increasing irradiation temperature. (C) 2010 Elsevier B.V. All rights reserved.