A research program to measure spin polarized fusion reactions in DIII-D

The use of spin polarized fuel could increase fusion reactivity by a factor of 1.5 and, owing to alpha heating, increase fusion Q in ITER even more. The use of polarized D and ³He in a DIII-D experiment avoids the complexities of handling tritium, while encompassing the same nuclear reaction spin-physics. Polarized fuels can be prepared by permeating optically-pumped ³He into an ICF shell pellet, and by either dynamically polarizing ⁷Li-D or generating pellets of frozen-spin H-D. The polarization lifetimes in cooled fuel capsules are long (days -to- months for D, days for ³He). Such cryogenically-frozen pellets can be injected vertically by special injectors that minimize depolarizing field gradients. Modeling shows that a readily producible plasma with T_i > 10 keV generates 14.7 MeV proton and 3.6 MeV alpha signals that are sensitive to spin-induced changes in differential cross sections with high accuracy. Additionally, all major reactor-relevant depolarization mechanisms are accessible for study in DIII-D, making it an attractive facility to assess this high impact reactor fueling technique experimentally.