W-He co-deposition was studied by means of in-vacuo thermal desorption spectroscopy. W-He co-deposited layers were produced at substrate temperatures varied from 400 K to 800 K with a 50 K temperature step. It was found that the He content decreases from ∼1.7 at. % at 400 K to ∼0.17 at. % at 750 K. At 800 K, an increase in the He content was observed, that should be caused by significant changes in the film structure. Helium TDS spectra had two main peaks with maxima in the 500-600 K range and at ∼960 K; the peaks observed are similar to those previously seen for He ion implantation in W. Several scaling expressions are proposed for He/W vs. T.
Different ion beam analysis techniques for the study of thin lithium-containing layers on top of fusion relevant materials are discussed and compared to each other. Elastic backscattering analysis (EBS) with protons is determined to be one of the most promising techniques and allows measurements of Li layers with thicknesses from ~100 nm up to ~600 μm, as shown by SIMNRA simulations. The best sensitivity for thin films (~100 nm) can be achieved using 4 MeV protons with 170° scattering detection angle for layers on Mo and W substrates, and 2 MeV for C substrates. Experimentally EBS measurements were successfully tested for Li films with thicknesses from ~50 nm up to ~400 nm after air exposure. The Li films become strongly inhomogeneous and require averaging over multiple measurements in nearby areas. This necessitates averaging over multiple nearby measurement points, and limits the overall precision of the measurement.
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