Berlin 2001 – scientific programme

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MO: Molekülphysik

MO 3: Reactive and Energy Transfer Processes

MO 3.9: Talk

Monday, April 2, 2001, 17:45–18:00, H1058

Interaction of H2+, H3+, D2+ and D3+ with stainless steel and graphite surfaces — •Abdul Qayyum, Christian Mair, Werner Schustereder, Andreas Goehlich, and Tilmann Märk — Institut für Ionenphysik, Universität Innsbruck, Technikerstr. 25, A-6020 Innsbruck

As plasma wall interactions in nuclear fusion devices are a limiting factor in reaching long confinement times due to the presence of impurities in the plasma by erosion of wall material and trapping of fuel in the surface layers, a detailed knowledge of the reactions and processes being involved is necessary. Here we report about measurements on the interaction of H2+, H3+ and their perdeutero-counterparts with various types of surfaces. Upon interaction with a graphite tile from the Tore Supra fusion reactor H2+ and H3+ are breaking up into H+. When plotting the relative abundance of each secondary ion versus the collision energy, the crossing point between the parent ion, H3+ or H2+, and the fragment ion H+ is a few eV higher for H3+ as compared to H2+. This reflects thermochemistry, as the binding energy of H3+ is about 1.6 eV larger than that of H2+. This also provides a tool for the determination of the transfer from translational to internal energy during the surface collision. In measurements with a stainless steel surface we have obtained similar results. Project carried out within the Association EURATOM/ ÖAW and partly supported by ÖAW and BMWF, Wien, Austria.