Accommodation of prompt alpha-particle loss in a compact stellarator power plant

Alpha loss is an important issue in stellarators, where the inherent non-axisymmetry of the magnetic geometry causes an appreciable magnetic field ripple along the flux surfaces inside the plasma. This results in a non-negligible fraction of alpha-particles being promptly lost from the plasma and hitting the plasma facing components (PFC) at energies close to their born value of 3.5 MeV. The PFC armor must not only accommodate the heat load from the alpha-particle flux but it must also accommodate the He implantation resulting from the high-energy alpha fluxes while providing the required lifetime. An effort is underway as part of the ARIES-CS study to characterize the alpha-particle loss for a compact stellarator and to explore engineering solutions to accommodate the impact of these alphas on the PFC’s. This paper summarizes the initial results from this effort.