OPERATIONAL LIMITS IN TOKAMAK MACHINES

Different operational limits of tokamaks are reviewed. The finally lim iting processes are hard or soft plasma disruptions or a strong x-ray source. The underlying events are explained as far as the physical cau ses are known. Treated are the density limit, the low-q-limit, the run away limit, the beta--limit, and the vertical displacement limit. In a ddition, the spontaneous MHD-instability and a hollow temperature prof ile situation are presented. The graphical displays are experimental r esults from the TEXTOR tokamak.