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
Hauptverfasser: 't Hoen, M.H.J., Mayer, M., Kleyn, A.W., Schut, H., Zeijlmans van Emmichoven, P.A.
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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.
ISSN:0029-5515
1741-4326
DOI:10.1088/0029-5515/53/4/043003