skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

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

Authors:
 [1];  [2];  [1]
  1. Department of Chemical Engineering, University of Massachusetts, Amherst, Massachusetts 01003-9303, USA
  2. Department of Nuclear Engineering, University of Tennessee, Knoxville, Tennessee 37996, USA
Publication Date:
Sponsoring Org.:
USDOE
OSTI Identifier:
1375965
Grant/Contract Number:
SC0008875
Resource Type:
Journal Article: Publisher's Accepted Manuscript
Journal Name:
Applied Physics Letters
Additional Journal Information:
Journal Volume: 111; Journal Issue: 8; Related Information: CHORUS Timestamp: 2018-02-14 23:45:52; Journal ID: ISSN 0003-6951
Publisher:
American Institute of Physics
Country of Publication:
United States
Language:
English

Citation Formats

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., 2017. 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.
@article{osti_1375965,
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 = {},
doi = {10.1063/1.4986956},
journal = {Applied Physics Letters},
number = 8,
volume = 111,
place = {United States},
year = 2017,
month = 8
}

Journal Article:
Free Publicly Available Full Text
This content will become publicly available on August 23, 2018
Publisher's Accepted Manuscript

Save / Share:
  • Molecular dynamics simulations have been used to generate a comprehensive database of surviving defects due to displacement cascades in bulk tungsten. Twenty-one data points of primary knock-on atom (PKA) energies ranging from 100 eV (sub-threshold energy) to 100 keV (~780 × Ed, where Ed = 128 eV is the average displacement threshold energy) have been completed at 300 K, 1025 K and 2050 K. Within this range of PKA energies, two regimes of power-law energy-dependence of the defect production are observed. A distinct power-law exponent characterizes the number of Frenkel pairs produced within each regime. The two regimes intersect atmore » a transition energy which occurs at approximately 250 × Ed. The transition energy also marks the onset of the formation of large self-interstitial atom (SIA) clusters (size 14 or more). The observed defect clustering behavior is asymmetric, with SIA clustering increasing with temperature, while the vacancy clustering decreases. This asymmetry increases with temperature such that at 2050 K (~0.5 Tm) practically no large vacancy clusters are formed, meanwhile large SIA clusters appear in all simulations. The implication of such asymmetry on the long-term defect survival and damage accumulation is discussed. In addition, <100> {110} SIA loops are observed to form directly in the highest energy cascades, while vacancy <100> loops are observed to form at the lowest temperature and highest PKA energies, although the appearance of both the vacancy and SIA loops with Burgers vector of <100> type is relatively rare.« less
  • In this report we compare time sampling and ensemble averaging as two different methods available for phase space sampling. For the comparison, we calculate thermal conductivities of solid argon and silicon structures, using equilibrium molecular dynamics. We introduce two different schemes for the ensemble averaging approach, and show that both can reduce the total simulation time as compared to time averaging. It is also found that velocity rescaling is an efficient mechanism for phase space exploration. Although our methodology is tested using classical molecular dynamics, the ensemble generation approaches may find their greatest utility in computationally expensive simulations such asmore » first principles molecular dynamics. For such simulations, where each time step is costly, time sampling can require long simulation times because each time step must be evaluated sequentially and therefore phase space averaging is achieved through sequential operations. On the other hand, with ensemble averaging, phase space sampling can be achieved through parallel operations, since each ensemble is independent. For this reason, particularly when using massively parallel architectures, ensemble sampling can result in much shorter simulation times and exhibits similar overall computational effort.« less