CONCEPT DEVELOPMENT AND PERFORMANCE ASSESSMENT OF THE POWER EXHAUST STRUCTURE OF THE ITER DIVERTOR

The ITER Divertor design is based on the idea of extinguishing the plasma flame in a gas target. According to this scheme a large part of the power entering the divertor region would be dissipated through atomic and molecular reactions. These processes must take place along the whole extension of the divertor throat, in order to limit the thermal loads and particle fluxes onto the target. Thus, the divertor channel walls have to be shaped in order to achieve an adequate heat removal capability and to allow an effective recirculation of the gas from the target to the upper part of the divertor region. This paper describes the main features of the Power Exhaust Structure of the ITER Divertor, which composes the side wall of the divertor channel. In the selected design, the side wall is formed by wing like plates (fins/vanes) twisted 45 degrees in the toroidal direction towards the incoming magnetic field lines. The shape and size of these vanes are determined by the requirement for providing a highly transparent wall, coupled with the need to minimize the thermal deflections and stresses of the structure induced by thermal and electromagnetic loads. The wings are made of copper and protected from the plasma by armor made from either Be or W. In this paper we present the basic features of the proposed design and report on the analyses carried out to assess the behavior of the vanes under the dominant loads. Also, the paper presents an assessment of the concept from the point of view of component fabrication, based on results of preliminary studies carried out to support the design of the ITER divertor.