IMPACT OF THE PASSIVE STABILIZATION SYSTEM ON THE DYNAMIC LOADS OF THE ITER FIRST WALL BLANKET DURING A PLASMA DISRUPTION EVENT/

In next-generation tokamak devices (i.e. ITER), passive stabilization of the plasma is required to mitigate the consequences of the plasma v ertical displacements and to reduce the occurrence of plasma disruptio ns. With this aim, two main design approaches have been considered. Th e first one (adopted in the ITER CDA design) consists of copper stabil ization loops (twin loops) attached to box-shaped blanket segments whi ch are electrically and mechanically separated along the toroidal dire ction. In the second design approach (under consideration for the ITER EDA design), relying on a lower plasma elongation, no specific stabil ization loops are required and the passive stabilization is achieved b y toroidally continuous components, in particular by the plasma facing wall of the blanket segments, electrically connected along the toroid al direction, thus allowing a toroidal current to flow during the elec tromagnetic transients. In both cases electrodynamic loads arise in th e blanket structures during plasma disruptions and/or vertical displac ement events, A comparison between the two design approaches has been carried out from the eddy-current and related load distribution viewpo int.