ERO Modelling of Local Deposition of Injected 13C Tracer at the Outer Divertor of JET

The 2004 tracer experiment of JET with injection of 13CH4 into H-mode plasma at the outer divertor has been modelled with the ERO code. EDGE2D solutions for inter-ELM and ELM-peak phases were used as plasma backgrounds. Local 2D deposition patterns at the vertical outer divertor target plate were obtained for comparison with post-mortem surface analyses. ERO also provides emission profiles for comparison with radially resolved spectroscopic measurements. Modelling indicates that enhanced re-erosion of deposited carbon layers is essential in explaining the amount of local deposition. Assuming negligible eective sticking of hydrocarbons, the measured local deposition of 20­34% is reproduced if re-erosion of deposits is enhanced by a factor of 2.5­7 compared to graphite erosion. If deposits are treated like the substrate, the modelled deposition is 55%. Deposition measurements at the shadowed area around injectors can be well explained by assuming there negligible re-erosion but similar sticking behaviour as on plasma-wetted surfaces.
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