Oxidation of beryllium and exposure of beryllium oxide to deuterium plasmas in PISCES B

Roth, J.; Doerner, R. P.; Baldwin, M.J.; Dittmar, T.; Xu, Henghui; Sugiyama, K.; Reinelt, M.; Linsmeier, Ch.; Oberkofler, M.

doi:10.1016/j.jnucmat.2013.01.228

Cited by 16 publications

(18 citation statements)

References 21 publications

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“…Note that only values for the lowest energy sites are listed in table 6, and in the case of an O interstitial, the DFT and ABOP values do not correspond to the same interstitial configuration. Furthermore, while the preferred sites in the ABOP certainly correspond to the global minimum energy sites for interstitials, that is not necessarily true for the DFT values, as we only considered a few selected sites.…”

Section: Point Defects In Beomentioning

confidence: 99%

Analytical bond order potential for simulations of BeO 1D and 2D nanostructures and plasma-surface interactions

Byggmästar

Hodille

Ferro

et al. 2018

J. Phys.: Condens. Matter

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An analytical interatomic bond order potential for the Be-O system is presented. The potential is fitted and compared to a large database of bulk BeO and point defect properties obtained using density functional theory. Its main applications include simulations of plasma-surface interactions involving oxygen or oxide layers on beryllium, as well as simulations of BeO nanotubes and nanosheets. We apply the potential in a study of oxygen irradiation of Be surfaces, and observe the early stages of an oxide layer forming on the Be surface. Predicted thermal and elastic properties of BeO nanotubes and nanosheets are simulated and compared with published ab initio data.

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Section: Point Defects In Beomentioning

confidence: 99%

Analytical bond order potential for simulations of BeO 1D and 2D nanostructures and plasma-surface interactions

Byggmästar

Hodille

Ferro

et al. 2018

J. Phys.: Condens. Matter

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“…To address this, a stored sample from prior experiments [20] was further analyzed using TDS. This sample had a history that included oxidation in atmosphere and subsequent exposure at ∼ 300 K to ∼ 30 eV deuterium ions in the periphery of a Pisces-B plasma.…”

Section: Discussionmentioning

confidence: 99%

“…This sample had a history that included oxidation in atmosphere and subsequent exposure at ∼ 300 K to ∼ 30 eV deuterium ions in the periphery of a Pisces-B plasma. In [20] the D depth profile for the target was measured using nuclear reaction analysis (NRA) (Refer to Fig. 6a in [20]), making Tmap modeling of the TDS thermal release possible.…”

Section: Discussionmentioning

confidence: 99%

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Thermal release of D2 from new Be-D co-deposits on previously baked co-deposits

Baldwin

Doerner

2015

Journal of Nuclear Materials

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Past experiments and modeling with the Tmap code in [1, 2] indicated that BeD co-deposited layers are less (time-wise) efficiently desorbed of retained D in a fixed low-temperature bake, as the layer grows in thickness. In Iter, beryllium rich co-deposited layers will grow in thickness over the life of the machine. Although, compared with the analyses in [1, 2], Iter presents a slightly different bake efficiency problem because of instances of prior tritium recover/control baking. More relevant to Iter, is the thermal release from a new and saturated co-deposit layer in contact with a thickness of previously-baked, less-saturated, co-deposit. Experiments that examine the desorption of saturated co-deposited overlayers in contact with previously baked under-layers are reported and comparison is made to layers of the same combined thickness. Deposition temperatures of ∼ 323 K and ∼ 373 K are explored. It is found that an instance of prior bake leads to a subtle effect on the under-layer. The effect causes the thermal desorption of the new saturated over-layer to deviate from the prediction of the validated Tmap model in [2]. Instead of the D thermal release reflecting the combined thickness and levels of D saturation in the over and under layer, experiment differs in that, i) the desorption is a fractional superposition of desorption from the saturated over-layer, with ii) that of the combined over and under-layer thickness. The result is not easily modeled by Tmap without the incorporation of a thin BeO inter-layer which is confirmed experimentally on baked BeD co-deposits using x-ray micro-analysis.

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“…For all energies (above 10 eV) and concentrations, the ratio Y Be /Y O spans around 0.5 between 0.3 and 0.7. Roth et al [34] reports Be+O is calculated as the average of the number of sputtered Be or O atoms in molecules (it is the same way of calculating the total sputtering yields Y Be+O presented in section 3.1). Figure 7 reports the evolution with the ion energy of the fraction of this sputtering relatively to the total sputtering Y chem Be+O /Y Be+O .…”

Section: Effect Of the D Concentration On The Sputtering Yieldmentioning

confidence: 99%

Molecular dynamics simulation of beryllium oxide irradiated by deuterium ions: sputtering and reflection

Hodille¹,

Byggmästar²,

Safi³

et al. 2019

J. Phys.: Condens. Matter

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The sputtering and reflection properties of wurtzite beryllium oxide (BeO) subjected to deuterium (D) ions bombardment at 300 K with ion energy between 10 eV and 200 eV is studied by classical molecular dynamics. Cumulative irradiations of wurtzite BeO show a D concentration threshold above which an 'unphysical dramatic' sputtering is observed. From the cumulative irradiations, simulation cells with different D concentrations are used to run non-cumulative irradiations at different concentrations. Using a D concentration close to the experimentally determined saturation concentration (0.12 atomic fraction), the simulations are able to reproduce accurately the experimental sputtering yield of BeO materials. The processes driving the sputtering of beryllium (Be) and oxygen (O) atoms as molecules are subsequently determined. At low irradiation energy, between 10 eV and 80 eV, swift chemical sputtering is dominant and produces mostly ODz molecules. At high energy, the sputtered molecules are mostly BexOy molecules (mainly BeO dimer). Four different processes are associated to the formation of such molecules: the physical sputtering of BeO dimer, the delayed swift chemical sputtering not involving D ions and the detachmentinduced sputtering. The physical sputtering of BeO dimer can be delayed if the sputtering event implies two interactions with the incoming ion (first interaction in its way in the material, the other in its way out if it is backscattered). The detachment-induced sputtering is a characteristic feature of the 'dramatic' sputtering and is mainly observed when the concentration of D is close to the threshold leading to this sputtering regime.

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Oxidation of beryllium and exposure of beryllium oxide to deuterium plasmas in PISCES B

Cited by 16 publications

References 21 publications

Analytical bond order potential for simulations of BeO 1D and 2D nanostructures and plasma-surface interactions

Analytical bond order potential for simulations of BeO 1D and 2D nanostructures and plasma-surface interactions

Thermal release of D2 from new Be-D co-deposits on previously baked co-deposits

Molecular dynamics simulation of beryllium oxide irradiated by deuterium ions: sputtering and reflection

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