Stress-induced hydrogen self-trapping in tungsten
RD Smirnov and SI Krasheninnikov, NUCLEAR FUSION, 58, 126016 (2018).
The molecular dynamics simulations of trapping of hydrogen atoms in tungsten are presented. The simulations reveal formation of platelet- like structures of self-trapped hydrogen induced by stresses in tungsten, in particular, those produced by dislocations, at the interstitial hydrogen concentrations similar to 0.3 - 1 at.%. The spontaneous hydrogen platelet formation in absence of dislocations and external stresses has been also observed at the higher hydrogen concentrations similar to 10 at.%. It is shown that the platelets can retain substantial quantities of hydrogen, exceeding trapping capacity of other non-cavity defects in tungsten. The properties of the hydrogen platelets formed in tungsten under various conditions are assessed and a formation mechanism is proposed. A model of hydrogen retention by the dislocation-induced structures is also presented, which describes retained quantities and outgassing dynamics of hydrogen in plasma exposed tungsten samples.
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