Divertor design plans for Eos stellarator

A non-resonant divertor system is being designed for the Eos quasi-axisymmetric stellarator. Research into magnetic field topology, system power balance calculations, and development of boron pebble extrusions to accommodate high heat and particle fluxes in the exhaust region are outlined. We use FIELDLINES to calculate the total magnetic field by applying the virtual casing calculation over the coil and plasma current contributions. FIELDLINES also performs field line tracing to illustrate particle trajectories beyond the last closed flux surface and exhaust locations via strike points on divertor target plates. We have conducted a study to evaluate how field line topology changes with respect to plasma and design parameters. System power balance calculations include input power from neutral beams and ECRH heating, as well as radiative losses. We can estimate the median and worst-case power magnitudes to apply along each field line, quantifying the heat flux using strike point density. Finally, we develop a conceptual design for a boron pebble extrusion system, including fundamental material calculations and experiments that outline the system’s capability in expected plasma conditions.