SMuK 2023 – scientific programme

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P: Fachverband Plasmaphysik

P 11: Poster I

P 11.31: Poster

Wednesday, March 22, 2023, 14:00–15:30, HSZ EG

Influence of beam profile on ion-driven permeation experiments — Philipp Sand and •Armin Manhard — Max Planck Insitute for Plasma Physics, 85748 Garching, Germany

Ion-driven permeation experiments can be used to determine e.g. solubility, diffusivity, defect binding energies and surface/interface transport in materials relevant for wall components in nuclear fusion devices. Especially under conditions where surface processes or trapping of hydrogen isotopes at defects play a significant role, such experiments are influenced by the distribution of the ion flux density across the irradiated surface. In suitable energy and ion flux ranges, the beam profile can be quantified by measuring the height profile across the sputter erosion crater of a bulk Cu sample. In this contribution, the beam profile in the high-current, ion-driven permeation setup TAPAS was determined. A 200 eV/D beam with a total current of 80 µA of D3⁺ ions was characterised and exhibits an averaged ion flux densitiy of 8x10¹⁹ D/m²s, while local values vary from 1x10¹⁹ to 3x10²⁰ D/m²s. A calculation scheme was implemented in the diffusion trapping code TESSIM-X. Permeation data for tungsten annealed at 2000 K was measured at 600 K and compared to simulations using the averaged ion flux as well as the detailed histogram of ion flux density. The relevance of the ion flux histogram is shown for 600 K, where trapping appearantly still plays a significant role. The best agreement between simulations and experiment was obtained for a trap concentration of 1.2x10^-4 and a binding energy of 1.45 eV. For high temperatures, where most traps are empty, both calculated solutions converge.