An experimental study of tungsten self sputtering

Laboratory experiments were carried out as part of the preparations of an oxygen glow discharge cleaning experiment in ASDEX Upgrade. They aimed at evaluating the effect of mixing the oxygen with helium, the collateral damage caused by the glow discharge, as well as the influence of impurities in the films being eroded. Oxygen concentrations below 20 % in helium are sufficient to achieve high erosion rates. The discharge can lead to the formation of oxide layers on surfaces which-as demonstrated for tungsten-can be rapidly reduced by post-treatment in a hydrogen discharge. For carbon, aluminum and iron the physical sputtering yield may become similar to the erosion yield of redeposited layers, but it is by more than one order of magnitude smaller for tungsten. Using a-B:C:H films with varying boron content, it was found that impurities can cause the erosion rate to drop by orders of magnitude.

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“…[30], He → Fe ---calc. [30], O → W • experimental [30,31,33], O → W • exp. this work, O → W -calculation [30], He → W ▽ exp.…”

Section: B Erosion Of W Al Fe and Cmentioning

confidence: 99%

Oxygen glow discharge cleaning in nuclear fusion devices

Hopf

Jacob

Rohde

2008

Journal of Nuclear Materials

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“…So, it is reasonable to assume that the sputtered atoms from the W-PFM are predominately originated from the bombardment of hydrogen and helium as well as the W clusters. In experiment, Wu et al [7] and Hechtl et al [8] respectively measured the sputtering yield with varying energy and angle of the incident particle. They all found the sputtering yield increased with increasing the incident energy of the coming particle, whereas the sputtering yield increased and then decreased as the incident angle changes from 0 • to 90 • .…”

Section: Introductionmentioning

confidence: 99%

Theoretical Simulations of Irradiation-Induced Sputtering at Tungsten Surface

Hua

Ding

et al. 2017

Chinese Journal of Chemical Physics

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The irradiation-induced sputtering and the structural damage at tungsten surface are investigated by using molecular dynamics simulations at the level of quantum mechanics. Our simulations indicate that the sputtered atoms appear when the energy of incident primary knock-on atom (PKA) is more than 200 eV and the incident angle of the PKA is larger than 65 •. Meanwhile, the irradiation-induced vacancies are less when the incident angle of PKA is in the range of 45 • −65 •. So, the optimum incident angles of PKA are suggested to reduce the irradiation-induced damage of the W surface. Furthermore, we find that the interstitials contained in the systems accelerate the sputtering whereas the intrinsic vacancies suppress the sputtering when the PKA is near the defects.

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Sputtering Yields

Eckstein

Topics in Applied Physics

145

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An experimental study of tungsten self sputtering

Cited by 14 publications

References 9 publications

Oxygen glow discharge cleaning in nuclear fusion devices

Oxygen glow discharge cleaning in nuclear fusion devices

Theoretical Simulations of Irradiation-Induced Sputtering at Tungsten Surface

Sputtering Yields

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