Title: Helium bubble size effects on the surface morphological response of plasma-facing tungsten

Abstract

Abstract We report a simulation study on the effects of helium (He) bubble size on the morphological evolution and pattern formation on the surface of tungsten used as a plasma-facing component (PFC) in nuclear fusion devices. We have carried out a systematic investigation based on self-consistent dynamical simulations of surface morphological evolution according to an atomistically-informed, 3D continuum-scale model that captures well the relevant length and time scales of surface nanostructure formation in PFC tungsten. The model accounts for PFC surface diffusion, driven by the biaxial compressive stress originating from the over-pressurized He bubbles in the near-surface region of PFC tungsten as a result of He plasma exposure, combined with the formation of self-interstitial atoms in tungsten that diffuse toward the PFC surface and the flux of surface adatoms generated as a result of surface vacancy-adatom pair formation upon He implantation; this transport of surface adatoms contributes to the anisotropic growth of surface nanostructural features due to the different rates of adatom diffusion along and across step edges of islands on the tungsten surface. Our detailed analysis reveals that varying the average He bubble size plays an important role in the PFC surface growth kinetics as well as the resultingmore » surface topography. Specifically, we find that an increase in the He bubble size leads to a deceleration in the growth rate of the tungsten nanotendrils that emanate from the PFC surface. We also find that the separation distance between the resulting surface features increases with increasing He bubble size, as well as over time. This coarsening effect is a thermally activated process resulting in an accurate description of the temperature dependence of the average surface feature separation by an Arrhenius relation.« less

Authors:

Patel, Omeet N. ;

• Search DOE PAGES for author "Patel, Omeet N."
• Search DOE PAGES for ORCID "0000-0002-0059-8351"

Dasgupta, Dwaipayan ;

• Search DOE PAGES for author "Dasgupta, Dwaipayan"
• Search DOE PAGES for ORCID "0000-0001-9405-922X"

Wirth, Brian D. ;

• Search DOE PAGES for author "Wirth, Brian D."
• Search DOE PAGES for ORCID "0000-0002-0395-0285"

Maroudas, Dimitrios

• Search DOE PAGES for author "Maroudas, Dimitrios"
• Search DOE PAGES for ORCID "0000-0001-9297-8839"

Publication Date:

Tue Jul 25 00:00:00 EDT 2023

Research Org.:

University of Massachusetts Amherst, MA (United States)

Sponsoring Org.:

USDOE Office of Science (SC), Fusion Energy Sciences (FES); USDOE Office of Science (SC), Advanced Scientific Computing Research (ASCR). Scientific Discovery through Advanced Computing (SciDAC)

OSTI Identifier:

1992401

Alternate Identifier(s):

OSTI ID: 1989269; OSTI ID: 1993932

Grant/Contract Number:  

SC0018421; SC0006661

Resource Type:

Published Article

Journal Name:

Materials Research Express (Online)

Additional Journal Information:

Journal Name: Materials Research Express (Online) Journal Volume: 10 Journal Issue: 7; Journal ID: ISSN 2053-1591

Publisher:

IOP Publishing

Country of Publication:

United Kingdom

Language:

English

Subject:

36 MATERIALS SCIENCE; tungsten; plasma-facing components; helium irradiation; fuzz formation; surface morphological evolution model; helium bubble formation