Abstract of talk
Shaping coils should be as far as possible from a stellarator or tokamak plasma, since a small separation complicates engineering and thereby increases costs. Coil complexity increases with coil-plasma separation in a way that depends strongly on the plasma shape, so plasma shapes should be chosen that can be supported by distant coils. The maximum feasible coil-plasma separation for a given plasma shape is closely related to a concept in tomography and image processing called the ‘discrete Picard condition’. In the present context, this condition derives from an operator that relates the externally produced magnetic field normal to the plasma surface to either the normal field or current on a coil surface. The discrete Picard condition is a restriction on the singular values and vectors of this operator. Numerical examples will be presented for both tokamak and stellarator cases. Counterintuitively, plasma shapes with low curvature and spectral width may have low “efficiency”, in the sense that shaping coils must be close, whereas plasma shapes with sharp edges may have high efficiency.
Room F-N6115, Origo building north 6th floor, Fysikgården 1
23 August, 2016, 13:30
23 August, 2016, 14:30