Plasma edge research on TEXTOR

The relations between plasma wall interaction and plasma core properties are studied by spectroscopic methods applied to the emission of neutral particles at the plasma boundary. The interdependence between the structure of the scrape-off layer (SOL), particle-fluxes and impurity release are analyzed. In particular, the importance of molecule formation for impurity release and particle recycling in a machine with an 'all-carbon' surrounding is shown. These mechanisms can lead to a stationary discharge with a cold plasma mantle ('detached plasma'), the properties of which are discussed. Local heating inside the SOL with ICRH is evident and some consequences for gas release and impurity generation are drawn. (author)