Plasma edge research on TEXTOR

TLDR

Spectroscopic analysis of neutral particle emission at the plasma boundary is used to study the relationship between plasma wall interaction and core properties. The interdependence of scrape‑off‑layer structure, particle fluxes, and impurity release is analyzed, showing that these mechanisms can produce a stationary discharge with a cold plasma mantle whose properties are discussed. Molecule formation is shown to be important for impurity release and particle recycling in an all‑carbon machine, the resulting mechanisms can lead to a detached plasma mantle, and local heating inside the SOL with ICRH produces gas release and impurity generation.

Abstract

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.