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

Abstract 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( 3 He,p) 4 He nuclear reaction at 3 He 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 μm, 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.