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 vertical displacements and to reduce the occurrence of plasma disruptions. With this aim, two main design approaches have been considered. The first one (adopted in the ITER CDA design) consists of copper stabilization loops (twin loops) attached to box-shaped blanket segments which are electrically and mechanically separated along the toroidal direction. In the second design approach (under consideration for the ITER EDA design), relying on a lower plasma elongation, no specific stabilization loops are required and the passive stabilization is achieved by toroidally continuous components, in particular by the plasma facing wall of the blanket segments, electrically connected along the toroidal direction, thus allowing a toroidal current to flow during the electromagnetic transients. In both cases electrodynamic loads arise in the blanket structures during plasma disruptions and/or vertical displacement events. A comparison between the two design approaches has been carried out from the eddy-current and related load distribution viewpoint.