Surface morphology and deuterium retention in tungsten exposed to high flux D plasma at high temperatures

Jia, Y.Z.; Temmerman, G.C. De; Luo, G.-N.; Xu, Huaping; Li, C.; Fu, Baoqin; Liu, W.

doi:10.1016/j.jnucmat.2014.11.079

Cited by 63 publications

(47 citation statements)

References 23 publications

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“…The presence of growing bubbles is confirmed by the blisters observed on the surface of the same sample by SEM analysis. In the present experiment as well as in a similar recent experiment [23], blisters, particular to high dose exposure, were observed. The SEM micrograph of the blisters is shown on figure 4 and additional micrographs are attached as on line supplementary material available at (stacks.iop.org/PSTOP/T167/014030/mmedia).…”

Section: Discussion and Conclusive Remarkssupporting

confidence: 87%

Microstructural modifications in tungsten induced by high flux plasma exposure: TEM examination

et al. 2016

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We have performed microstructural characterization using transmission electron microscopy (TEM) techniques to reveal nanometric features in the sub-surface region of tungsten samples exposed to high flux, low energy deuterium plasma. TEM examination revealed formation of a dense dislocation network and dislocation tangles, overall resulting in a strong increase in the dislocation density by at least one order of magnitude as compared to the initial one. Plasmainduced dislocation microstructure vanishes beyond a depth of about 10 μm from the top of the exposed surface where the dislocation density and its morphology becomes comparable to the reference microstructure. Interstitial edge dislocation loops with Burgers vector a 0 /2〈111〉 and a 0 〈100〉 were regularly observed within 6 μm of the sub-surface region of the exposed samples, but absent in the reference material. The presence of these loops points to a co-existence of nanometric D bubbles, growing by loop punching mechanism, and sub-micron deuterium flakes, resulting in the formation of surface blisters, also observed here by scanning electron microscopy.S Online supplementary data available from stacks.iop.org/PSTOP/T167/014030/mmedia

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Section: Discussion and Conclusive Remarkssupporting

confidence: 87%

Microstructural modifications in tungsten induced by high flux plasma exposure: TEM examination

et al. 2016

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“…Treating the exponent also as free fit parameter an exponent of 0.62 ± 0.02 and 0.57 ± 0.02 is obtained for the unblistered and blistered case. Fitting the two data sets with a mean exponent of 0.60 ± 0.03, illustrated as green doted line in figure 7 and using equation (15) with an adapted exponent, results in a ratio of 0.76 ± 0.02 between Γ sink and Γ imp . Hence, within the framework of the model, the additional loss flux Γ sink amounts to approximately 80 % of the implanted flux Γ imp .…”

Section: B3 Analytical Hydrogen Retention Modelmentioning

confidence: 99%

Influence of near-surface blisters on deuterium transport in tungsten

et al. 2017

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The effect of near-surface blisters on deuterium transport in tungsten is studied by means of nuclear reaction analysis (NRA) and scanning electron microscopy (SEM). Gentle deuterium plasma loading of different durations and subsequent NRA depth profiling is performed in heavily pre-blistered and unblistered areas on self-damaged tungsten samples.Comparison of the deuterium depth profiles reveals a considerable reduction of the deuterium transport into the bulk due to the presence of near-surface blisters. SEM and NRA results identify the enhanced re-emission of deuterium from the sample due to open blisters as the underlying mechanism which reduces the deuterium flux into the bulk. Based on a simple analytical hydrogen retention model, the re-emitted deuterium flux by open blisters in the here conducted experiment, is determined to be 80 % of the implanted deuterium flux. In addition, the deuterium flux into the bulk is reduced by 60 % compared to the unblistered case. As a consequence, deuterium retention studies carried out under blister-facilitating conditions should account for surface morphology which reduce the deuterium uptake.

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“…Under this assumption, one can assign the high temperature TDS peak (usually seen in low flux exposures around 700-900 K) to the release from bubbles [16]. However, the TDS spectra obtained after the high flux exposures, at high temperature (above 600 K) and/or high dose (above 10 26 D/m 2 ), reveal broadening or presence of extra peaks above 900 K [13,17]. These high temperature release stages cannot be simply explained by detrapping from voids with the binding energy of 2.0 eV, while there are no reasons to assume the presence of any stronger traps than voids/cavities.…”

Section: Model Descriptionmentioning

confidence: 99%

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

et al. 2016

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Recently developed numerical model, based on the dislocation-driven nucleation of gas bubbles, is used to analyse experimental results on deuterium retention in tungsten under ITER relevant plasma exposure conditions. Focus is put on understanding the relation between exposure temperature and flux on primary features of thermal desorption spectra: peak positions and intensities of the desorption flux. The model allows one to relate the peak positions with the size of plasma induced deuterium bubbles and envisage exposure conditions (temperature and flux) for their formation. Based on the performed analysis, dedicated experimental conditions to validate the model are proposed.

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Surface morphology and deuterium retention in tungsten exposed to high flux D plasma at high temperatures

Cited by 63 publications

References 23 publications

Microstructural modifications in tungsten induced by high flux plasma exposure: TEM examination

Microstructural modifications in tungsten induced by high flux plasma exposure: TEM examination

Influence of near-surface blisters on deuterium transport in tungsten

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

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