Migration of Eroded Materials and Layer Formation by Deposited Impurities

3 Migration of Eroded Materials and Layer Formation by Deposited Impurities 

Since a tokamak or a stellarator represents almost a closed system, the majority of eroded particles must be deposited somewhere in the machine. Therefore, when calculating the life time of plasma facing components it is misleading to consider erosion only. E.g., taking an extreme case on the tip of 

On a given area we have to consider a simultaneous flow of eroded (rero) and deposited (Jdep) particles and the effective erosion rate reg is then reg = rero — Aep. The erosion rate is given by the hydrogen ion flow Tr and the impurity ion flow J] out of the plasma and the respective erosion yields Yr and Y according to 

Deposition depends on the sticking coefficient S for the impinging impurity ion flow R 

The ratio Rero = rCTO// i..p determines whether we have a net-erosion or a net-deposition zone 

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