Temperature dependence of surface morphology and deuterium retention in polycrystalline ITER-grade tungsten exposed to low-energy, high-flux D plasma

Surface topography and deuterium retention in polycrystalline ITER-grade tungsten have been examined after exposure to a low-energy (38 eV/D), high-flux (10(22) D/m(2) s) deuterium plasma with ion fluences of 10(26) and 10(27) D/m(2) at various temperatures. The methods used were scanning electron microscopy equipped with focused ion beam, thermal desorption spectroscopy. and the D(He-3,p)He-4 nuclear reaction at He-3 energies varied from 0.69 to 4.0 MeV. During exposure to the D plasma at temperatures in the range from 320 to 815 K, small blisters of size in the range from 0.2 to 5 mu m, depending on the exposure temperature and ion fluence, are formed on the W surface. At an ion fluence of 10(27) D/m(2), the deuterium retention increases with the exposure temperature, reaching its maximum value of about 10(22) D/m(2) at 500 K, and then decreases below 10(19) D/m(2) at 800 K. (C) 2011 Elsevier B.V. All rights reserved.