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Title: Thermal conductivity of tungsten: Effects of plasma-related structural defects from molecular-dynamics simulations

We report results on the lattice thermal conductivities of tungsten single crystals containing nanoscale-sized pores or voids and helium (He) nanobubbles as a function of void/bubble size and gas pressure in the He bubbles based on molecular-dynamics simulations. For reference, we calculated lattice thermal conductivities of perfect tungsten single crystals along different crystallographic directions at room temperature and found them to be about 10% of the overall thermal conductivity of tungsten with a weak dependence on the heat flux direction. The presence of nanoscale voids in the crystal causes a significant reduction in its lattice thermal conductivity, which decreases with increasing void size. Filling the voids with He to form He nanobubbles and increasing the bubble pressure leads to further significant reduction of the tungsten lattice thermal conductivity, down to ~20% of that of the perfect crystal. The anisotropy in heat conduction remains weak for tungsten single crystals containing nanoscale-sized voids and He nanobubbles throughout the pressure range examined. Analysis of the pressure and atomic displacement fields in the crystalline region that surrounds the He nanobubbles reveals that the significant reduction of tungsten lattice thermal conductivity in this region is due to phonon scattering from the nanobubbles, as well asmore » lattice deformation around the nanobubbles and formation of lattice imperfections at higher bubble pressure.« less
Authors:
 [1] ;  [2] ;  [1]
  1. Univ. of Massachusetts, Amherst, MA (United States)
  2. Univ. of Tennessee, Knoxville, TN (United States)
Publication Date:
Grant/Contract Number:
SC0008875
Type:
Accepted Manuscript
Journal Name:
Applied Physics Letters
Additional Journal Information:
Journal Volume: 111; Journal Issue: 8; Journal ID: ISSN 0003-6951
Publisher:
American Institute of Physics (AIP)
Research Org:
Univ. of Massachusetts, Amherst, MA (United States)
Sponsoring Org:
USDOE Office of Science (SC), Fusion Energy Sciences (FES) (SC-24)
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; Plasmas; Interatomic Potentials; Nanofluidics; Phonon Scattering; Transition Metals
OSTI Identifier:
1473863
Alternate Identifier(s):
OSTI ID: 1375965

Hu, Lin, Wirth, Brian D., and Maroudas, Dimitrios. Thermal conductivity of tungsten: Effects of plasma-related structural defects from molecular-dynamics simulations. United States: N. p., Web. doi:10.1063/1.4986956.
Hu, Lin, Wirth, Brian D., & Maroudas, Dimitrios. Thermal conductivity of tungsten: Effects of plasma-related structural defects from molecular-dynamics simulations. United States. doi:10.1063/1.4986956.
Hu, Lin, Wirth, Brian D., and Maroudas, Dimitrios. 2017. "Thermal conductivity of tungsten: Effects of plasma-related structural defects from molecular-dynamics simulations". United States. doi:10.1063/1.4986956. https://www.osti.gov/servlets/purl/1473863.
@article{osti_1473863,
title = {Thermal conductivity of tungsten: Effects of plasma-related structural defects from molecular-dynamics simulations},
author = {Hu, Lin and Wirth, Brian D. and Maroudas, Dimitrios},
abstractNote = {We report results on the lattice thermal conductivities of tungsten single crystals containing nanoscale-sized pores or voids and helium (He) nanobubbles as a function of void/bubble size and gas pressure in the He bubbles based on molecular-dynamics simulations. For reference, we calculated lattice thermal conductivities of perfect tungsten single crystals along different crystallographic directions at room temperature and found them to be about 10% of the overall thermal conductivity of tungsten with a weak dependence on the heat flux direction. The presence of nanoscale voids in the crystal causes a significant reduction in its lattice thermal conductivity, which decreases with increasing void size. Filling the voids with He to form He nanobubbles and increasing the bubble pressure leads to further significant reduction of the tungsten lattice thermal conductivity, down to ~20% of that of the perfect crystal. The anisotropy in heat conduction remains weak for tungsten single crystals containing nanoscale-sized voids and He nanobubbles throughout the pressure range examined. Analysis of the pressure and atomic displacement fields in the crystalline region that surrounds the He nanobubbles reveals that the significant reduction of tungsten lattice thermal conductivity in this region is due to phonon scattering from the nanobubbles, as well as lattice deformation around the nanobubbles and formation of lattice imperfections at higher bubble pressure.},
doi = {10.1063/1.4986956},
journal = {Applied Physics Letters},
number = 8,
volume = 111,
place = {United States},
year = {2017},
month = {8}
}