V. Dubinko

Dislocation mechanism of deuterium retention in tungsten under plasma implantation

V. Dubinko, D. Terentyev, P. Grigorev, A. Bakaev, G. Van Oost, F. Gao, D. Van Neck, E. Zhurkin

Journal of Physics: Condensed Matter

26, 395001

2014

A1

Abstract

We have developed a new theoretical model for deuterium (D) retention in tungsten-based alloys on the basis of its being trapped at dislocations and transported to the surface via the dislocation network with parameters determined by ab initio calculations. The model is used to explain experimentally observed trends of D retention under sub-threshold implantation, which does not produce stable lattice defects to act as traps for D in conventional models. Saturation of D retention with implantation dose and effects due to alloying of tungsten with, e.g. tantalum, are evaluated, and comparison of the model predictions with experimental observations under high-flux plasma implantation conditions is presented.

DOI

http://dx.doi.org/10.1088/0953-8984/26/39/395001

Deuterium accumulation in tungsten under low-energy high-flux plasma exposure

P. Grigorev, V. Dubinko, D. Terentyev, A. Bakaev, E. Zhurkin

JOURNAL OF SURFACE INVESTIGATION-X-RAY SYNCHROTRON AND NEUTRON TECHNIQUES

8 (2), 234–238

2014

A1

Abstract

The accumulation of deuterium implanted in tungsten is simulated within the framework of kinetic diffusion theory. The influence of the tungsten microstructure (dislocation density and impurity concentration) on the process of deuterium capture and accumulation is considered. It is established that, under the chosen irradiation conditions, deuterium accumulation in the near-surface region is determined by capture at defects formed during implantation. The deuterium concentration gradient, together with the material microstructure, determines its accumulation in tungsten. Variation in the dislocation density and impurity concentration does not affect the simulation results, which is, first, related to the fact that the model used does not contain alternative mechanisms for the formation and growth of vacancy clusters under the subthreshold irradiation mode. The simulation results are compared with experimental data, and ways of improving the model are discussed in order to explain the deuterium-saturation effect for high fluences (more than 10²³ m⁻²).

DOI

http://dx.doi.org/10.1134/S102745101402013X

Dislocations mediate hydrogen retention in tungsten

D. Terentyev, V. Dubinko, A. Bakaev, Y. Zayachuk, W. Van Renterghem, P. Grigorev

Nuclear Fusion

54 (4), 042004

2014

A1

Abstract

In this letter, a comprehensive mechanism for the nucleation and growth of bubbles on dislocations under plasma exposure of tungsten is proposed. The mechanism reconciles long-standing experimental observations of hydrogen isotopes retention, essentially defined by material microstructure, and so far not fully explained. Hence, this work provides an important link to unify material's modelling with experimental assessment of W and W-based alloys as candidates for plasma facing components.