Entwicklung einer Methode zur Berechnung der elektromagnetischen Kraefte durch Magnetfeldaenderungen in ferromagnetischen Strukturen und Anwendung dieser Methode auf den Plasmaabbruch in einem Tokamakreaktor

Abstract

DEMO is the only step between ITER and a prototype of a commercial fusion reactor. The high neutron fluence characteristic for DEMO imposes the choice of a martensitic steel as structural material. The steel MANET (MArtensitic for NET) has been chosen for the European DEMO blanket designs. MANET is a ferromagnetic material with a nonlinear magnetic behaviour which alters the distribution of the magnetic field inside and outside the blanket structure in such a way that during a plasma disruption, as eddy currents are induced in the blanket structure, strong electromagnetic forces occur whose magnitude can be substantially greater than in the case without ferromagnetic structural material. Within the activities of the Karlsruhe Research Centre for the DEMO solid breeder blanket design, a computer code which can take into account the presence of ferromagnetic material has been developed. The new code - named AENEAS (advanced eddy-current nonlinear electromagnetic analysis system) - has been derived from CARIDDI/FZK, a code already in use for electromagnetic calculations with non-magnetic conducting structures. The magnetic properties of MANET in relation to reactor conditions are discussed together with the modelling of the magnetization curve. The mathematical and numerical formulation of the code as well as its structure are then explained. Furthermore, the results of calculations performed for two test problems - a magnetostatic and a transient nonlinear problem - are presented and compared with the corresponding experimental data. Finally, the code AENEAS has been applied to the Karlsruhe DEMO Solid Breeder Blanket design for a reference case of a plasma disruption. The results show that during a plasma disruption, even if the mechanical load on the structure increases due to the presence of ferromagnetic material, the mechanical integrity of the blanket is preserved. (orig.)51 refs.Available from TIB Hannover: ZA 5141(5683) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman