Plasma physics models for the early-stage design and optimization of Eos: a sub-breakeven, deuterium-deuterium, beam-target fusion, stellarator neutron source facility

On the path to a fusion pilot plant, Thea Energy plans to build Eos, a sub-breakeven, deuterium-deuterium, beam-target fusion, stellarator neutron source facility for producing tritium and other valuable radioisotopes. A set of 1-D plasma physics models are coupled and used to design the operating point of the facility and predict performance. Analytic and approximate models are sufficient to capture the leading-order effects. Models of 1-D profile-dependent neutral beam stopping, ion beam slowing down, beam-target fusion, electron-ion classical heat transfer, energy confinement (ISS04), beam pressure, beam heating of ions and electrons, beam-beam fraction, and neutral beam injection and gyrotron heating electrical efficiencies are included. A potentially advantageous plasma-physics regime is described in which modern precisely-quasisymmetric stellarators, new hightemperature superconductors, ITER-derived neutral beam injection, and new high-frequency gyrotrons enable a suitible target plasma with hot electrons, cold ions, peaked density and temperature profiles, and high beam-injected ion density. It appears possible at this time for a facility with a medium-scale and medium-strength stellarator whose required facility electric power is less than 40 MW to produce 2.5 × 10^17 neutrons/second for the production of radioisotopes. With the addition of a tritium breeding blanket, such a facility could produce 0.2 grams/day or 70 grams/year of tritium.