Optimisation of confinement in a fusion reactor using a nonlinear turbulence model

摘要

The confinement of heat in the core of a magnetic fusion reactor is optimisedusing a multidimensional optimisation algorithm. For the first time in such astudy, the loss of heat due to turbulence is modelled at every stage usingfirst-principles nonlinear simulations which accurately capture the turbulentcascade and large-scale zonal flows. The simulations utilise a novel approach,with gyrofluid treatment of the small-scale drift waves and gyrokinetictreatment of the large-scale zonal flows. A simple near-circular equilibriumwith standard parameters is chosen as the initial condition. The figure ofmerit, fusion power per unit volume, is calculated, and then two controlparameters, the elongation and triangularity of the outer flux surface, arevaried, with the algorithm seeking to optimise the chosen figure of merit. Atwo-fold increase in the plasma power per unit volume is achieved by moving tohigher elongation and strongly negative triangularity.