Overview and Status of the Spin Polarized Fusion Program

The Spin Polarized Fusion (SPF) program aims to experimentally measure deuterium (D) and helium-3 (³He) nuclei polarization survival in DIII-D plasma. The spin polarized (SP) fuel has their nuclei spin aligned parallel to the local magnetic field. Leveraging SP fuel, fusion reaction cross-section can be enhanced by 50%, with a resultant increase in the tokamak fusion power yield. The SPF program is a collaborative effort amongst Jefferson Lab (JLab), University of Virginia (UVA), Oak Ridge National Laboratory (ORNL), and University of California Irvine (UCI). JLab is preparing polarized D pellets, and so far, has designed, built, and commissioned the irradiation beamline. UVA is responsible for supplying polarized ³He pellets, ORNL is building a cryogenic injection gun for SP fuel, and UCI is coordinating the project, plasma scenario development and charged fusion product diagnostics. The plan is to inject polarized D & ³He pellets into DIII-D plasma and measure relative poloidal distribution of the deconfined charged fusion product to infer the spin polarization survival. Besides D-³He scenario, recent work [Nucl. Fusion 65 (2025) 046005] shows that lifetime measurements are feasible using reactions between an injected unpolarized neutral D beam and polarized D nuclei from a pellet.