Crystal orientation dependence of surface modification in molybdenum mirror irradiated with helium ions

M. Miyamoto, H. Takaoka, K. Ono, S. Morito, N. Yoshida, H. Watanabe, A. Sagara

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13 Citations (Scopus)

Abstract

The crystal orientation dependence on a surface damage in molybdenum mirror has been investigated under the irradiation with 3 keV helium ions to a fluence of 1022 ions/m2. A strong correlation between the surface roughening and the grain orientation was confirmed from SEM-EBSD analysis. It was found that significant surface roughening including crater-like depressions is formed on the grain surfaces with crystalline planes close to (1 0 0), while relatively smooth surface remains on grains with the other directions. In contrast, the reflectivity measurement of the single crystal molybdenum with a spectroscopic ellipsometry showed smaller reduction in (1 0 0) sample than in (1 1 0) and (1 1 1) samples. The smallest helium desorption in (1 0 0) sample was also detected with thermal desorption spectroscopy in comparison with them in (1 1 0) and (1 1 1) samples, which indicates (1 1 0) and (1 1 1) samples include the large amount of defects acting as effective trapping site for He atoms. A cross-sectional TEM observation actually showed a relatively large bubbles at sub-surface regions of (1 1 0) sample. These results indicate that the optical reflectivity should be affected by not only a top surface profile but also internal radiation damages such as high density of helium bubbles.

Original languageEnglish
Pages (from-to)297-300
Number of pages4
JournalJournal of Nuclear Materials
Volume455
Issue number1-3
DOIs
Publication statusPublished - Dec 2014

All Science Journal Classification (ASJC) codes

  • Nuclear and High Energy Physics
  • Materials Science(all)
  • Nuclear Energy and Engineering

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