Numerische Simulation von Plasma-Zusammenbruechen fuer die Berechnung der Strukturbelastung in Tokamak-Fusionsreaktoren

A method is developed for the numerical simulation of plasma disruptions in tokamak fusion devices. The simulation of the second phase of the disruption, namely the current quench, allows for the first time a realistic analysis of the loads in the structure caused by disruptions. Up to now, the plasma behavior was prescribed in the input of codes used to analyse the structural loads. Because of the fact that the time dependend behavior of the disruption strongly depends on the electrical properties of the surrounding structure, the computational method has to take into account these mutual coupling effects of plasma and structure. To solve this problem, a dynamic plasma model was developed. This model has been integrated in the three dimensional finite element eddy-current code CARIDDI. Therefore, the new method finds a niche between codes that are developed to simulate only the plasma in great detail, and the currently used eddy current codes, where the plasma behavior is given as an input. The plasma is represented by reduced magnetohydrodynamic equations. The equations of electrodynamics and of plasma movement are solved separately in time. For the electrodynamics, a finite element approach has been developed that easily allows the inductive coupling of the two dimensional plasma and the three dimensional structure. The vertical movement of the plasma is solved by a rigid body approach, in which the accelerating forces on the plasma are linearized around the equilibrium. For the prescription of the free plasma-vacuum interface, a ''Volume-Of-Fluid'' method was applied. This method allows a fast and exact detection of the moving plasma boundary during disruption. To simulate the plasma scraping off when contacting the first wall, a special model has been developed. Due to methodical limits, only the toroidal component of the halo current can be considered. However, the poloidal component has been taken into account using an empirical approach. (orig.)140 refs.Available from TIB Hannover: ZA 5141(5867) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman