Design and Construction of a Two Coil Table-Top Stellarator

A new table-top stellarator experiment called ETOS has been designed with one planar and one helical coil to produce an approximate quasi-isodynamic field with five-fold symmetry. The new stellarator configuration has been identified by perturbing the analytic coil parameters and using field line following to identify closed flux surfaces. Moreover, the shape of the employed coils has been optimized for reduced neoclassical transport, a quasi-isodynamic magnetic field structure, and feasibility of construction. VMEC equilibrium reconstructions demonstrate a rotational transform of 0.15, and acceptable neoclassical confinement with ε_eff^3/2 values close to 0.1. By considering currents of up to 10 kA-turns, the expected magnetic field strength will be 0.09 T on axis, allowing plasma heating by 2.45 GHz ECRH. The helical coil has been designed based on 10 gauge wire and will be supported by a 3D printed structure. The vessel will consist of straight glass tubes, connected by 3D printed stainless steel sections that are shaped to fit the equilibrium flux surfaces. A combination of the size, small coil number and ample space around the coils, the vessel can be easily accessed making it an ideal testbed to explore the feasibility of 3D printed vacuum vessels for plasma experiments.