Reduced deuterium retention in self-damaged tungsten exposed to high-flux plasmas at high surface temperatures
We investigated the effect of surface temperature on deuterium retention in self-damaged tungsten exposed to high-flux deuterium plasmas. The retention saturates at a W4+ fluence of about 3 × 1017 m−2 and is strongly reduced for the present high surface temperatures of 800-1200 K as compared with pr...
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Veröffentlicht in: | Nuclear fusion 2013-04, Vol.53 (4), p.43003-9 |
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Format: | Artikel |
Sprache: | eng |
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Zusammenfassung: | We investigated the effect of surface temperature on deuterium retention in self-damaged tungsten exposed to high-flux deuterium plasmas. The retention saturates at a W4+ fluence of about 3 × 1017 m−2 and is strongly reduced for the present high surface temperatures of 800-1200 K as compared with previous experiments at 470-525 K. Combination of nuclear reaction analysis (NRA), thermal desorption spectroscopy and positron annihilation Doppler broadening (PADB) was used to investigate the reduction in deuterium retention. The NRA showed a strong reduction of retention at the surface at high surface temperatures. The PADB measurements suggest that during plasma exposure defects are mobile and cluster into larger clusters containing up to a few tens of vacancies. The Tritium Migration Analysis Program 7 simulations show that trapping and de-trapping rates are very high for defects with trapping energies below ∼1.5 eV. The strong reduction in retention seems to be caused by the reduced amount of mono-vacancies and small vacancy clusters in combination with their strong depopulation due to thermal trapping and de-trapping. |
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ISSN: | 0029-5515 1741-4326 |
DOI: | 10.1088/0029-5515/53/4/043003 |