Unterberg, B. (Corresponding author)FZJ* ; Institut für Plasmaphysik (Jülich) ; Association EURATOM - Forschungszentrum Jülich ; Universität (Bochum)

1995
Forschungszentrum Jülich

Report No.: Juel-3036

Abstract: The concept of a cold radiating plasma mantle might help to solve the problem of energy exhaust in a fusion reactor. Line radiation of impurities localized at the boundary of the bulk plasma could distribute the heating power onto the whole vessel wall and avoid dangerous heat loads at the plasma facing components as limiters or divertor plates. Important requirements have to be fulfilled within such a concept: on the one hand a stationary impurity concentration at the edge on a high level, sufficient to radiate a substantial fraction of the heating power and to reduce the plasma temperature at the boundary and the convective heat flow to the limiters or divertor plates, but on the other hand a limitation of the central impurity concentration to values compatible with ignition in a fusion reactor at the same time. First experiments at the tokamak TEXTOR with neon as the radiating impurity gave evidence for the feasibility of this concept. Within this work further experiments with neon and a comparison with silicon as the radiating impurity have been performed. The results are discussed with the help of model calculations to judge these two elements with respect to their suitability for radiation cooling by characterizing the mechanisms of their plasma wall interaction and the properties of radiation and transport

Keyword(s): radiation ; cooling ; impurity ; plasma sheath ; Textor Tokamak ; injection ; neon ; silicon

1. Plasmaphysik (IEF-4)