Verteilung des Wärmeflusses auf eine optimierte Limiteroberfläche und Struktur der Plasmarandschicht

The heat load on plasma-facing components is a key issue for forthcoming fusion experiments. In this work the heat flux on the pump limiter in TEXTOR-94 is measured by a newly developed digital thernography system and these results are compared withtheoretical models. The limiter is shaped in such a way as to keep the heat load of the plasma-wetted area low; this is achieved by reducing the angle of incidence of the magnetic field lines with respect to the limiter surface to less than 1° for the first 10 mm of the scrape-off-layer (SOL). This small angle of incidence enhances all effects of toroidal non-uniformity as given e.g. by the magnetic field ripple. Extensive modelling explains well the observed heating pattern on the limiter surface due to the ripple effect. In contrast to expectations from density and temperature distributions in the SOL and at the edge of the confined region, an excessive power density is deposited an the first few millimetres near the roof tip of the limiter. Physical effects which could cause this phenomenon are discussed