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

Sub-surface structures of ITER-grade W (Japan) and re-crystallized W after ITER-similar low-energy and high-flux D plasma loadings

“…This distorted layer as in fig. 2d and e, but without blisters and cracks already exists for the unirradiated sample [13], not shown in this work. The Bending of the crystal lattices and cracks like that observed in recrystallised W at about 400-500 K could not be seen.…”

“…The D retention of these specimens was determined by TDS and NRA using the reaction D( 3 He,p) 4 He by scanning the 3 He energy from 690 keV up to 4 MeV. The results are presented in [12,13,16]. The surface topography and the 3D morphology of the plasma-exposed tungsten were analysed by SEM.…”

“…The data on D retention in re-crystallised W and ITER-grade W measured by NRA and TDS [12,13,16] are shown in Fig. 1.…”

“…Next, in this work, the surface changes of ITER-grade W are analysed and compared with re-crystallized W from [11] after identical D loading, resulting in totally different structures but similar D retentions. The D retention in W is analysed by nuclear reaction analyse (NRA) and thermal desorption spectroscopy (TDS) [12,13]. Additional experiments are performed in this work to solve the remaining open questions.…”

Numerical analysis of TDS spectra under high and low flux plasma exposure conditions

“…However under the conditions where dislocationdriven mechanism is not active, other microstructural features may act as nucleation sites for bubble nucleation. For example in work [12], the observation of bimodal size distribution of blisters was attributed to an alternative mechanisms -cavity growth and coalescence on grain boundary interfaces.…”