Minimum coil complexity for a given quasisymmetry quality
In plain words
The most precise magnetic shapes need complicated, tightly curved coils that are expensive and hard to build accurately. How simple the coils can be while keeping good confinement is not known.
Precise statement
Quantify the trade-off between quasisymmetry error and coil engineering metrics: minimum coil-plasma distance relative to minor radius, maximum coil curvature, number of coils and allowed fabrication tolerance. For example, determine whether planar or other simple coil sets can achieve quasisymmetry error below 1e-2 at reactor aspect ratio and coil-plasma spacing. An answer is a Pareto frontier from global optimization.
What would settle it
A globally optimized database of configurations and coils establishing the frontier, cross-checked by independent codes.
Status in the literature
Unverified note
Large databases of quasisymmetric configurations with coils (QUASR, 2024, arXiv:2409.04826) map part of this frontier.