Ultrafine tungsten as a plasma-facing component in fusion devices: effect of high flux, high fluence low energy helium irradiation

TitleUltrafine tungsten as a plasma-facing component in fusion devices: effect of high flux, high fluence low energy helium irradiation
Publication TypeJournal Article
Year of Publication2014
AuthorsO. El-Atwani, S. Gonderman, M. Efe, G. De Temmerman, T. Morgan, K. Bystrov, D. Klenosky, T. Qiu, J.P Allain
JournalNuclear Fusion
Volume54
Issue8
Pagination083013
Date PublishedAUG
Abstract

This work discusses the response of ultrafine-grained tungsten materials to high-flux, high-fluence, low energy pure He irradiation. Ultrafine-grained tungsten samples were exposed in the Pilot-PSI (Westerhout et al 2007 Phys. Scr. T128 18) linear plasma device at the Dutch Institute for Fundamental Energy Research (DIFFER) in Nieuwegein, the Netherlands. The He flux on the tungsten samples ranged from 1.0 x 10(23)-2.0 x 10(24) ions m(-2) s(-1), the sample bias ranged from a negative (20-65) V, and the sample temperatures ranged from 600-1500 degrees C. SEM analysis of the exposed samples clearly shows that ultrafine-grained tungsten materials have a greater fluence threshold to the formation of fuzz by an order or magnitude or more, supporting the conjecture that grain boundaries play a major role in the mechanisms of radiation damage. Pre-fuzz damage analysis is addressed, as in the role of grain orientation on structure formation. Grains of (1 1 0) and (1 1 1) orientation showed only pore formation, while (0 0 1) oriented grains showed ripples (higher structures) decorated with pores. Blistering at the grain boundaries is also observed in this case. In situ TEM analysis during irradiation revealed facetted bubble formation at the grain boundaries likely responsible for blistering at this location. The results could have significant implications for future plasma-burning fusion devices given the He-induced damage could lead to macroscopic dust emission into the fusion plasma.

DOI10.1088/0029-5515/54/8/083013
Division

PSI

Department

PSI-E

PID

e0a48284a35be04a993d2e22cc420fa1

Alternate TitleNucl. Fusion

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