Interpretation of Be migration studies at JET and validation of an integrated numerical model for plasma impurity transport and wall composition dynamics

Fusion experiments with wall cladding of different chemical elements face the problem of material mixing by the plasma–wall interaction. Understanding of experiments that investigate this long term material re-distribution require an iterative approach that takes the local erosion, the global transport of material by the scrape-off layer (SOL) plasma and the local re-deposition into account. We present a model that combines parameterized DIVIMP calculations and a simplified sputtering model to simulate the time evolution of first wall material migration in a fusion experiment. The simulations are benchmarked by Be evaporation experiments performed previously at JET. The time evolution of the spectroscopically measured Be erosion fluxes for 800 s total plasma time at the main wall and inner divertor can be reproduced by the model using an extended calculation grid for DIVIMP and an increased cross-field diffusivity for impurity ions in the SOL. Discrepancies were found in the outer divertor region.