Plasma wall interaction and its control by wall conditioning

The coexistence of fusion plasmas with the material walls surrounding it an d their interaction has many destructive consequences both for the walls an d for the plasma. Plasma wall interaction (PWI) is, however, a necessary in gredient of fusion plasmas on the earth. This contribution addresses the ma in PWI processes by which impurities are released from the walls. Following this redeposition of eroded material and local material transport is discu ssed. Finally wall conditioning will be discussed which offers the possibil ity to control some of the plasma wall interaction processes.