Carbon erosion experiments in the ITER relevant flux regime

Kleyn, Aart W.1; Shumack, A.E.1; Westerhout, J.1; Vijvers, W.A.J.1; Brezinsek, S2; Lopes Cardozo, N.J.1; Goedheer, W.J.1; de Groot, B.1; van der Meiden, H.J.1; Schram, D.C.1; Whyte, D.G.3; van Rooij, G.J.1 1Netherlands; 2Germany; 3United States

The FOM Institute for Plasma Physics Rijnhuizen is building the linear plasma generator Magnum-PSI for fundamental research on Plasma Surface Interactions (PSI) in the unexplored regime of plasma conditions as expected in the divertor of ITER. The heart of this device will be a high flux plasma source that is being developed at the forerunner Pilot-PSI. In this contribution we report on a breakthrough in plasma production. Thomson scattering (density and temperature) and emission spectroscopy (velocity) measurements were combined to demonstrate plasma fluxes ranging over two orders of magnitude around the fluxes expected for the ITER divertor (1023- 1025 m-2s-1) and temperatures from 0.1 to 5 eV. Carbon samples (Fine Grain Graphite, R 6650, SGL Carbon Group) were exposed to this unique Pilot-PSI hydrogen plasma jet. The samples were clamped to a water-cooled heat sink. The C-H band (around 431 nm) and the hydrogen Balmer-gamma line (434.0 nm) were measured close to the surface to monitor the chemical erosion; an infrared camera was used to monitor the target surface temperature. We will present results of these experiments, which are carbon erosion yields over the entire flux range that is accessible in Pilot-PSI for different target surface temperature. This dataset reaches and even exceeds the flux range relevant to ITER.

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