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How simple the coils can be while keeping good confinement is not known.","posed_since":"","precise":"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 $10^{-2}$ at reactor aspect ratio and coil-plasma spacing. An answer is a Pareto frontier from global optimization.","problem_ref":"79b028108bc0f27f6435934cbc1b4edf7dac65b5bac67b7a6de27ee2cda7874d","references":"","settled_by":"A globally optimized database of configurations and coils establishing the frontier, cross-checked by independent codes.","status_note":"Large databases of quasisymmetric configurations with coils (QUASR, 2024, arXiv:2409.04826) map part of this frontier.","title":"Minimum coil complexity for a given quasisymmetry 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