This figure shows the sensitivity of the neoclassical ion particle flux at the r/a= 0.5 surface to local perturbations of B. This information could be used to obtain an engineering tolerance on magnetic field errors or to inform optimization.
Seminar by Elizabeth Paul
Title: Adjoint methods for neoclassical stellarator calculations
Seminar by Elizabeth Paul, University of Maryland, USA
The design of modern stellarator experiments requires numerical optimization to minimize neoclassical radial transport and bootstrap current in addition to many other physics properties. As stellarator geometry is fully 3D, requiring many parameters to describe the magnetic geometry, computing variations of neoclassical quantities can be very expensive. Adjoint methods greatly reduce the cost of such an optimization, allowing gradients of output quantities (such as the bootstrap current) with respect to parameters (such as the magnetic geometry) to be computed very efficiently. I will discuss the application of an adjoint equation in the stellarator neoclassical code, SFINCS, for efficient gradient-based optimization. A resulting W7-X-like configuration with minimal bootstrap current will be presented. I will discuss several other applications of the adjoint method for neoclassical calculations, including local sensitivity analysis, correction of discretization error, and efficient ambipolar solutions.
N6115, seminar room, Fysik Origo
12 June, 2018, 10:00
12 June, 2018, 11:00