Planar coil design for the Helios stellarator fusion power plant

A new candidate coil set for Thea Energy, Inc.’s quasi-axisymmetric fusion power plant, “Helios”, is discussed. Every coil is planar and convex. The coil set consists of 12 encircling coils that link the plasma to generate net toroidal flux, and 324 shaping coils. The shaping coils are all circular and have the same diameter, 133.7 cm. A 120 cm coil to plasma minimum distance constraint is enforced during optimization to leave room for a tritium breeding blanket and neutron shield. The maximum magnetic field strength in the coils is 19.4 T. A free-boundary equilibrium reconstruction from this coil set is provided. The coil set is optimized to be compact, requiring 14 billion Ampere-meters worth of high-temperature superconducting tape required in the coil windings.