Providing Highly Polarized ³He and D Fuels for the DIII-D Spin-Polarized Fusion Experiment

Work from Garcia et. al. ([Nucl. Fusion 63 (2023) 026030] and [Nucl. Fusion 65 (2025) 046005]) has demonstrated the ability to ascertain nuclear fuel polarization survival via the relative measurements of charged fusion products. A new spin-polarized fusion (SPF) experiment is in preparation ([Nucl. Fusion 63 (2023) 076009]) to measure polarization survivability in the DIII-D Tokamak reactor. In this experiment, the selected isospin-mirror reaction, ³He + D → α + p, is initiated with hyper-polarized ³He and ⁷LiD. A team at the University of Virginia is employing spin exchange optical pumping (SEOP) to achieve a high initial ³He polarization (up to 85%). A novel technique for diffusing the polarized ³He into sub-millimeter-sized polymer shells will increase the overall fuel density. The final ³He polarization, after diffusion, is expected to be near 65%. A separate team at Jefferson National Laboratory is utilizing dynamic nuclear polarization (DNP) to polarize ⁷LiD pellets. An apparatus is being constructed to simultaneously expose irradiated ⁷LiD samples to microwaves and monitor the sample polarization via NMR. The final sample is expected to be approximately 70% vector polarized. I will provide an overview and status of these parallel efforts.