Hydrogen Retention In Plasma-Sprayed Tungsten

Abstract

Abstract.Deuterium retention in plasma-sprayed tungsten (PSW) was investigated by means of the thermodesorption technique. . The observed retention in PSW is four times higher than in polycrystalline tungsten (PCW). An additional high-temperature peak was found in the thermodesorption spectra of PSW (at 1050 K). The nature of the high-temperature peak and the mechanism of higher retention in PSW are discussed.

Benefits and Challenges of the Use of High-Z Plasma Facing Materials in Fusion Devices

“…dynamic gas balance measurements, where the retention is derived from the difference of the puffed and the pumped amount of gas [28] show a similar reduction, in line with expectations from laboratory measurements on the deuterium retention in W [29,30,31]. In Alcator C-Mod the hydrogen retention was studied using a 'static' gas balance method, where all pumps are switched off or separated from the vacuum vessel and the retained amount is calculated from the injected gas puff and from the pressure inside the vacuum level after the discharge [32].…”

“…This is due to the strong suppression of D co-deposition with carbon as investigated by post-mortem surface analysis [26,27]. Additionally, PCW (AUG) [27] 200 eV D VPS-W [29] 200 eV D PCW [30,31] Mo (Alcator C-Mod) [32] 100 eV, D Mo [33] FIGURE 2. Deuterium retention in W and Mo.…”

Deuterium retention in tungsten used in ASDEX Upgrade: comparison of tokamak and laboratory studies

“…This suggests that blistering can be somehow suppressed on the machined surface as well. Finally, D retention in AUG W materials as a function of incident fluence is summarized in Figure 4 together with relevant laboratory data [16,17,19,27,[29][30][31][32] and an estimation of D in W compiled by the ITPA SOL/DIV topical group [33]. The thin CMSII-W coating shows that D retention determined by TDS (total retention) agrees relatively well to that measured by NRA (surface retention).…”

“…W coatings are usually expected to have a higher density of defects such as vacancies, voids and pores compared to PC-W, which may work as D trapping site. For instance, the mass density of VPS-W is usually 90-95% of theoretical one [14][15][16][17], and a high density of micrometer-scale pores in the coatings can be always confirmed by SEM. The D concentration with the order of 10 -1 at.% observed in the AUG VPS-W agrees with the laboratory result gained by Alimov et al for the same VPS-W coating [17].…”

“…The gray shaded region corresponds to an estimation of D retention in W based on laboratory experiments compiled by ITPA SOL/DIV topical group [33]. results together with the data previously obtained from AUG divertor probes [7,34] and laboratory results [16,17,19,27,[30][31][32]. The gray shaded region corresponds to an estimation of D retention in W based on laboratory experiments compiled by ITPA SOL/DIV topical group [33].…”