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P: Plasmaphysik
P 24: Plasma-Wand Wechselwirkung 3
P 24.4: Vortrag
Mittwoch, 29. März 2006, 15:30–15:45, 1002
Hydrogen retention in rhenium doped tungsten — •Anna Golubeva, Matej Mayer, and Joachim Roth — MF, Max-Planck-Institut für Plasmaphysik, Boltzmannstr. 2, 85748 Garching
Tungsten is a candidate first wall material for nuclear fusion devices due to its low erosion yield by hydrogen bombardment and high sputtering threshold. Hydrogen accumulation in plasma-facing materials is one of the key aspects of the fusion reactor operation.
Hydrogen retention in Re doped W is of interest, because W transmutes into Re under energetic neutron irradiation. The situation in a fusion reactor was simulated using W-Re alloys with 1, 5 and 10 % contamination of Re (W-%Re). A common feature of all tungsten-rhenium alloys, independently of the Re contamination, was the presence of voids and cavities in the bulk of the material.
Hydrogen retention in the tungsten-rhenium alloys was investigated by means of the thermodesorption technique. The alloys were irradiated by deuterium ions with energies of 200 eV and 3 keV per deuteron, achieving fluences in the range 1022 to 1024 D/m2 at room temperature. Long-time irradiation of W-%Re with low-energy deuterium ions leads to filling of the voids in the bulk by material. The observed retention in W-%Re is an order of magnitude higher than in polycrystalline tungsten (PCW). An additional high-temperature peak was found in the thermodesorption spectrum of W-%Re at 800 K. The nature of the high-temperature peak, the mechanism of higher retention in W-%Re and the mechanism of void filling with material are discussed.