Effect of high-flux H/He plasma exposure on tungsten damage due to transient heat loads

The thermal shock behaviour of tungsten exposed to high-flux plasma is studied using a high-power laser. The cases of laser-only, sequential laser and hydrogen (H) plasma and simultaneous laser plus H plasma exposure are studied. H plasma exposure leads to an embrittlement of the material and the ap...

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Bibliographic Details
Published in:Journal of nuclear materials 2015-08, Vol.463, p.198-201
Main Authors: De Temmerman, G., Morgan, T.W., van Eden, G.G., de Kruif, T., Wirtz, M., Matejicek, J., Chraska, T., Pitts, R.A., Wright, G.M.
Format: Article
Language:English
Subjects:
Exposure
Fracture mechanics
Hydrogen embrittlement
Lasers
Melting
Networks
Thermal shock
Tungsten
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Summary:The thermal shock behaviour of tungsten exposed to high-flux plasma is studied using a high-power laser. The cases of laser-only, sequential laser and hydrogen (H) plasma and simultaneous laser plus H plasma exposure are studied. H plasma exposure leads to an embrittlement of the material and the appearance of a crack network originating from the centre of the laser spot. Under simultaneous loading, significant surface melting is observed. In general, H plasma exposure lowers the heat flux parameter (FHF) for the onset of surface melting by ∼25%. In the case of He-modified (fuzzy) surfaces, strong surface deformations are observed already after 1000 laser pulses at moderate FHF=19MJm−2s−1/2, and a dense network of fine cracks is observed. These results indicate that high-fluence ITER-like plasma exposure influences the thermal shock properties of tungsten, lowering the permissible transient energy density beyond which macroscopic surface modifications begin to occur.
ISSN:0022-3115
1873-4820
DOI:10.1016/j.jnucmat.2014.09.075