FIRE, a next step option for magnetic fusion

Abstract

The next major frontier in magnetic fusion physics is to explore and understand the strong non-linear coupling among confinement, MHD stability, self-heating, edge physics and wave-particle interactions that is fundamental to fusion plasma behavior. The Fusion Ignition Research Experiment (FIRE) design study has been undertaken to define the lowest cost facility to attain, explore, understand and optimize magnetically confined fusion-dominated plasmas. FIRE is envisioned as an extension of the existing advanced tokamak (AT) program that could lead to an attractive magnetic fusion reactor. FIRE activities have focused on the physics and engineering assessment of a compact, high-field tokamak with the capability of achieving Q≈10 in the Elmy H-mode for a duration of ∼1.5 plasma current redistribution times (skin times) during an initial burning plasma science phase, and the flexibility to add AT hardware (e.g. lower hybrid current drive) later. The configuration chosen for FIRE is similar to that of ARIES-RS, the US Fusion Power Plant study utilizing an AT reactor. The key ‘AT’ features are: strong plasma shaping, double null pumping divertors, low toroidal field (TF) ripple (<0.3%), internal control coils and space for wall stabilization capabilities. The reference design point is R o=2.14 m, a=0.595 m, B t( R o)=10 T, I p=7.7 MA with a flat top time of 20 s for 150 MW of fusion power. The baseline magnetic fields and pulse lengths can be provided by wedged BeCu/OFHC TF coils and OFHC poloidal field (PF) coils that are pre-cooled to 80 K prior to the pulse and allowed to warm up to 373 K at the end of the pulse. A longer term goal of FIRE is to explore AT regimes sustained by non-inductive current drive (e.g. lower hybrid current drive) at high fusion gain ( Q>5) for a duration of one to three current redistribution times.