Similarities in divertor erosion/redeposition and deuterium retention patterns between the tokamaks ASDEX Upgrade, DIII-D and JET

The similar poloidal patterns of divertor erosion and redeposition of the A SDEX Upgrade, DIII-D and JET tokamaks are examined by comparing hydrogen is otope retention at the surfaces of divertor tiles. The outer divertor strik e point undergoes net erosion. The inner divertor is a region of net redepo sition, with deuterium co-deposition rates similar to 20 mu g m(2) s(-1) fo r all three devices; despite their differences in geometry, size and plasma facing materials. This extrapolates to an unacceptably high tritium retent ion rate in a DT burning steady state tokamak.