Nucleation and growth of hydrogen bubbles on dislocations in tungsten under high flux low energy plasma exposure

Research output: Contribution to journalArticle

Authors

Institutes & Expert groups

  • NSC - Kharkov Institute of Physics and Technology
  • UGent - Universiteit Gent
  • UGent - University Ghent - Department of Applied Physics
  • PbPU - Peter the Great St.Petersburg Polytechnic University - Russia

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Abstract

A new mechanism for the nucleation and growth of hydrogen (H) bubbles on dislocations under plasma exposure of tungsten was recently proposed on the basis of direct ab initio calculations. Density functional theory calculations demonstrated that H atoms are strongly bound to a screw dislocation core and exhibit fast one-dimensional migration along its line. Once the number of hydrogen atoms trapped on a dislocation segment exceeds eight, the emission of a jog occurs thereby converting a pure HN cluster into a HN+1-jog configuration. On the basis of these results a kinetic model was formulated to evaluate the conditions (i.e., range of temperature and flux exposure) for the transformation of pure H clusters into supercritical hydrogen–vacancy clusters attached to the dislocation line. In this work, a parametric study employing the kinetic nucleation model was performed to derive the hydrogen bubble formation energy function that offers the best agreement with available experimental results. The obtained results allow one to rationalize the depth and temperature dependence of the experimentally observed hydrogen deposition after high flux low energy plasma exposure for ITER relevant conditions.

Details

Original languageEnglish
Pages (from-to)96-99
Number of pages3
JournalNuclear Instruments and Methods in Physics Research Section B
Volume352
DOIs
Publication statusPublished - 1 Jun 2015

Keywords

  • Hydrogen retention, Tungsten, Bubble

ID: 3368203