Reflection properties of small hydrocarbons impinging on tungsten and carbon surfaces

Sticking coefficients of deuterium from CD2+ are quantified on fusion relevant plasma sprayed tungsten and carbon fibre composite in the incident energy range from about 0–100 eV. The samples that were cut from ASDEX-Upgrade tiles are exposed to a beam of CD2+ of specific incident energy, Einc, in the tandem mass spectrometer BESTOF in Innsbruck. Nuclear reaction analysis is performed ex-situ at IPP Garching for the quantification of deuterium content. The deuterium content difference measured on a spot before and after ion-beam exposure of the sample is assigned to the above mentioned species of hydrocarbon molecules sticking on the surface, allowing the calculation of the sticking probability of a specific deuterated molecular ion. The sticking coefficient, S, is found to depend on the incident energy and shows a maximum of about S ∼ 0.4 around Einc = 30 eV on CFC and about S ∼ 0.1 near Einc = 20 eV in case of PSW.