The Fusion Advanced Studies Torus (FAST): A proposal for an ITER satellite facility in support of the development of fusion energy

The successful development of ITER and DEMO scenarios requires a preparatory activity on devices smaller than ITER, with sufficient flexibility and capable of investigating the peculiar physics of burning plasma conditions. The aim of the Fusion Advanced Studies Torus (FAST) proposal is showing that preparation of ITER scenarios and development of new expertise for DEMO design and R and D can be effectively implemented on a new facility that: a) will work with Deuterium plasmas, avoiding the problems associated with the use of Tritium, and will investigate non linear dynamics that are relevant for the understanding of alpha particle behaviors in burning plasmas by using fast ions accelerated by heating and current drive systems; b) will work in a dimensionless parameter range close to that of ITER; c) will test technical innovative solutions for the first wall/divertor directly relevant for ITER and DEMO, such as full-tungsten plasma facing components and advanced liquid metal divertor target; d) will exploit advanced regimes with long pulse duration with respect to the current diffusion time; e) will provide a test bed for ITER and DEMO diagnostics; all fast particles expected in FAST plasmas (p, D, ³He) are assumed to be diagnosed; as in ITER, diagnostics of fast particles require intensive R and D, that can be carried out on FAST with reduced costs and development time; f) will provide an ideal framework for model and numerical code benchmarks, verification and validation in ITER and DEMO relevant plasma conditions. The scientific rationale of the FAST conceptual design will be discussed. The choice of high equilibrium magnetic field B = 7.5 T, the consequent possibility of operating routinely at high plasma current I_p = 6.5 MA, high plasma density and moderate temperature, while maintaining a significant fusion performance at Q > 1 together with the possibility of extended pulse operations (up to 80 resistive times) will elucidate the capability for FAST of reaching its objectives in a flexible and cost-effective way. (author)