Location and Strength of Impurity Sources

Impurity generation by erosion of materials from plasma facing components is an important issue for a fusion device with respect to 

detrimental effects on the plasma performance due to fuel dilution and/or radiation losses at the plasma core. 

A major challenge to experiments is the understanding of erosion mechanisms in the complex environment of a fusion device. Predictions about erosion in ITER by numerical modeling are based on related experimental findings in tokamaks, on laboratory measurements (e.g., ion beams or linear plasma devices) and the theoretical understanding of underlying mechanisms. Most experimental data on erosion yields in tokamaks have been obtained from 

in situ measurements of impurity fluxes based on spectroscopic methods (fluxes, velocities, penetration depth into the plasma) and 

post mortem analysis of wall tiles (layer thickness, surface composition). 

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