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 pla sma flame in a gas target. According to this scheme a large part of th e power entering the divertor region would be dissipated through atomi c and molecular reactions. These processes must take place along the w hole extension of the divertor throat, in order to limit the thermal l oads and particle fluxes onto the target. Thus, the divertor channel w alls have to be shaped in order to achieve an adequate heat removal ca pability and to allow an effective recirculation of the gas from the t arget to the upper part of the divertor region. This paper describes t he 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) twist ed 45 degrees in the toroidal direction towards the incoming magnetic field lines. The shape and size of these vanes are determined by the r equirement for providing a highly transparent wall, coupled with the n eed to minimize the thermal deflections and stresses of the structure induced by thermal and electromagnetic loads. The wings are made of co pper 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 vane s 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 th e ITER divertor.