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International Journal for Uncertainty Quantification

Impact factor: 1.000

ISSN Print: 2152-5080
ISSN Online: 2152-5099

Open Access

International Journal for Uncertainty Quantification

DOI: 10.1615/Int.J.UncertaintyQuantification.2018025120
Forthcoming Article

Uncertainty quantification for incident helium flux in plasma-exposed tungsten

Ozgur Cekmer
Oak Ridge National Laboratory
Khachik Sargsyan
Sandia National Laboratories
Sophie Blondel
University of Tennessee, Knoxville
Habib Najm
Sandia National Laboratories
David Bernholdt
Oak Ridge National Laboratory
Brian Wirth
University of Tennesee, Knoxville

ABSTRACT

In this work, the surface response of a tungsten plasma-facing component was simulated by a cluster-dynamics code, Xolotl, with a focus on quantifying the impact of uncertainty in one of the input parameters to Xolotl, namely the incident helium flux. The simulated conditions involve a tungsten surface exposed to 100 eV helium ion implantations with a flux of either 4x10^22 or 4x10^25 He m^(-2)s^(-1). Two sources were used to describe the implanted helium depth distribution in tungsten, either molecular dynamics (MD) or a binary collision approximation code, the Stopping and Range of Ions in Matter (SRIM). The aim of this work is to evaluate and examine uncertain predictions on the helium retention based on these two different modeling methodologies that either neglect electronic energy loss or the crystalline structure of the solid, respectively. An embedded model-form error approach was pursued here in order to arrive at predictions that account for variability due to the two different data sources, and the impact of this model-form uncertainty in incident helium flux on Xolotl output was presented for the two implantation fluxes.