Influence of H+ ion irradiation on the surface and microstructural changes of a nuclear graphite

Transmission electron microscopy, Raman and X-ray photoelectron spectroscopy studies on neutron irradiated polycrystalline graphite

“…4a and b strongly suggest the presence of hydroxyl groups on the surface. Oxygenated graphite surface forms C ¼O and C À O, which originates decomposition of adsorbed hydroxyl species during irradiation (Zilibotti et al, 2009). The chemical reactions are expected to occur during irradiation for the Fig.…”

“…The broadening of C1s core line in irradiated graphite is associated with the formation of dangling bonds and disturbed electric field around the vacancies arising from displacement of carbon atoms from lattice during irradiation, which is represented through components of chemical bonding derived from sp 2 and sp 1 hybridizations at 285.3 eV and sp 3 , sp 2 and sp 1 at 290.0 eV. Yang et al (2012) showed a wide range of structural change such as localised evolution of sp 3 CÀ C bonding and oxygen containing carbon bonds, possibly at the edges of deteriorated graphite crystallites in nuclear graphite under energetic H þ ion irradiation environment. Further, Yang et al also noted the inversion of sp 3 CÀ C bonding to sp 2 CÀ C bonding through thermal annealing induced by energetic displacing radiations (Yang et al, 2012).…”

“…Yang et al (2012) showed a wide range of structural change such as localised evolution of sp 3 CÀ C bonding and oxygen containing carbon bonds, possibly at the edges of deteriorated graphite crystallites in nuclear graphite under energetic H þ ion irradiation environment. Further, Yang et al also noted the inversion of sp 3 CÀ C bonding to sp 2 CÀ C bonding through thermal annealing induced by energetic displacing radiations (Yang et al, 2012). The result on localised transformation of carbon bonding is in concurrence with the results observed in previous studies.…”

Investigation of SOL plasma interaction with graphite PFC

“…The schematic diagram of the experimental setup is shown in Fig. 1 and the details have been described elsewhere [5]. The ECR plasma was generated with operating deuterium gas pressure of 1 mTorr, the microwave power of 400 W, and a coil current of 110 A.…”

“…While the sputtering yield has been estimated by Roth's model [2] that is assumed a plane surface without consideration of morphological change, the graphite morphology is easily to be changed as conical tip [3,4], crack [5], and surface erosion [6] because energetic deuterium actively reacts and bonds with a carbon atom. Then it is expected that the morphological changes of graphite induce the increase of the sputtering yield due to the increase of local angle of ion incidence [7,8].…”