Advances in the FAST program

FAST (Fusion Advanced Studies Torus) is a proposal for a Satellite Facility which can contribute the rapid exploitation of ITER and prepare ITER and DEMO regimes of operation, as well as exploiting innovative DEMO technology. FAST operates with high performance H-Mode (BT up to 8.5 T; I_P up to 8 MA) as well as Advanced Tokamak operation (I_P=3 MA), and full non inductive current scenario (I_P=2 MA) [1]. The project is based on a dominant 30 MW of ICRH, 6 MW of LH and 4 MW of ECRH. Helium gas at 30K is used for cooling the resistive copper magnets, which dimensions have been determined to limit the coil temperature at the end of the longest pulses (pulse length up to 170 s). The peak current density in the reference H-mode is about 45 MA/m². The Finite Element Method (FEM) has been employed to analyse the stresses of the load assembly structure [2] using the ANSYS code. Due to the full structural cooperation, the Toroidal Field Coils, Central Solenoid and mechanical structure, have been modelled as a whole, using mechanical and thermal smeared properties. Structural analyses were performed at the most significant times of the operating scenario. The FW consists of a bundle of coaxial tubes armoured with 4 mm plasma-sprayed tungsten. The conceptual design of the FW, emphasising the more relevant aspects of the mechanical solution, is reported. The expected high power flux (18 MW/m²) in the divertor target plates [3] impose the use of monoblock W tiles actively cooled. An optimization of the divertor configuration, as a result of upgraded plasma edge modelling, is presented. The engineering aspects and the principal features of the divertor revised design are discussed.