THE TOROIDAL FIELD MAGNET CONCEPT OF ASDEX UPGRADE

ASDEX Upgrade (UG), a divertor tokamak with a minor plasma radius of a=0.5 m and a plasma current of 1.2 to 1.5 MA, is intended to succeed ASDEX. A major target of this experiment is to investigate a reactor-compatible plasma boundary. This requires according to /1/ a toroidal field (B O ) at the plasma centre normalized to the aspect ratio (A) of B o /A ≈ 1.2. The optimum with due allowance for physical requirements and technical constraints of the complete tokamak system was obtained in this case for B o =3.9 T (A=3.25) and a plasma radius of 1.63m. The toroidal field (TF) magnet designed to meet these requirements is presented here. Aspects of its turnover structure such as force transfer, coil housing and access to the plasma vessel are described. The coil concept developed in collaboration with industry is also presented, in particular the conductor concept and the current terminals and water manifold designs. Finally, the results of the cooling and stress analysis are summarized.