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A. Golczewski:
"Ion-Induced erosion of fusion relevant surfaces";
Vortrag: 17th Intern. Workshop on Inelastic Ion- Surface Collisions (IISC-17), Ile de Porquerolles/F; 25.09.2008; in: "Book of Abstracts, 17th Intern. Workshop on Inelastic Ion- Surface Collisions (IISC-17)", (2008), S. 72.

The interaction of fusion plasmas with
surrounding wall materials in the vacuum vessel
constitutes one of the main remaining engineering
problems in future thermo-nuclear fusion experiments,
such as ITER [1]. The use of graphite or carboncomposites
as plasma-facing materials in magnetically
confined fusion plasmas (e.g. in ITER) lead to severe
problems. These problems are associated to
* chemical sputtering, i.e. strongly enhanced
erosion due to hydrocarbon formation in the interaction
with fuel atoms and ions with carbon atoms from the
wall, and
* tritium (T) retention: Fuel retention can occur
due to implantation and diffusion into plasma facing
materials or deposition of eroded material and codeposition
of fuel atoms. Indeed, the main retention
processes identified so far are linked to carbon erosion,
transport and re-deposition, leading to fuel trapping in
the re-deposited layers [2].
For ITER a material mix is currently foreseen:
Beryllium (Be) for the first wall, Tungsten (W) on the
upper divertor regions and the dome, and carbon (C) on
the divertor plates. However, if T (fuel) retention
remains unacceptably high with the C targets, a full
tungsten device could be contemplated in a second
phase.