Deposition of 13C Tracer in the JET MkII-HD Divertor
Migration of 13C has been investigated at JET by puffing 13CH4 into the outer midplane at the end of the 2007 campaign. 13C deposition profile was measured with Secondary Ion Mass Spectrometry (SIMS) and Rutherford BackScattering (RBS) techniques. 13C was mainly found on tile 1 and near the Outer Strike Point (OSP) on tile 7. The 13C transport was modelled with the EDGE2D/NIMBUS code and a number of migration paths were transport was modelled with the EDGE2D/NIMBUS code and a number of migration paths were identified. These pathways are: (1) migration through the main chamber Scrape-Off Layer (SOL), (2) migration through the Private Flux Region (PFR) aided by ExB drifts and (3) neutral migration originating near the strike points. The underlying assumption is that erosion/re-deposition cycle occurs along the targets and leads to a multi-step migration of 13C towards the separatrix called 'walking' which creates carbon neutrals at the OSP and results in 13C deposition in the PFR.