Deposition of 13C Tracer in the JET MkII-HD Divertor

Migration of 13C has been investigated at JET by injecting 13C labelled methane at the outer divertor base at the end of the 2009 campaign. The 13C deposition profiles on CFC divertor tiles were measured with secondary ion mass spectrometry and Rutherford backscattering techniques. 13C was mainly deposited near the puffing location on the outer divertor base tiles. High amounts of 13C were also found at the outer vertical target: bottom of the lower and at the top of the upper plates. 33% of the puffed 13CH4 was instantly pumped out by the divertor cryopump which is close to the the pump duct entrance. The global 13C transport in the torus was modelled with the EDGE2D/EIRENE and DIVIMP codes and the local 13C migration in the vicinity of the injection location with the ERO code. The DIVIMP and EDGE2D simulations show strong prompt deposition of 13C directly adjacent to the injection point, as well as in the far SOL along both the inner and outer divertor targets. In addition, the measured 13C deposition along the outer divertor wall tiles is qualitatively reproduced. However, EDGE2D and DIVIMP do not predict any deposition along the divertor surfaces facing the private plasma on the inner floor tile and inboard of the outer strike point on Tile 5. The ERO calculations also indicate that majority of the deposition occurs close to the injection location on the vertical face of the LBSRP tile and the horizontal part of Tile 6.
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