Researchers at the Princeton Plasma Physics Laboratory, led by J.F. Parisi, have made significant strides in the field of nuclear fusion by demonstrating that using spin-polarized deuterium-tritium (D-T) fuel can dramatically enhance tritium burn efficiency (TBE) while maintaining fusion power output. This breakthrough, published in the journal ‘Nuclear Fusion’, reveals that a fuel mix with more deuterium than tritium can increase TBE by at least tenfold compared to traditional unpolarized fuels.
The study highlights a critical challenge in fusion energy: the balance between tritium inventory and fusion power density. Previous research indicated that reducing the tritium fraction could improve TBE, but this often came at the cost of lower power density. Parisi’s team found that TBE increases nonlinearly as the tritium fraction decreases, while fusion power density rises approximately linearly with the D-T cross-section. This means that by optimizing the fuel mix and employing spin-polarization techniques, it is possible to enhance efficiency without sacrificing power output.
For instance, in an ARC-like tokamak scenario producing 481 MW of fusion power, the minimum startup tritium inventory was initially calculated at 0.69 kg with a conventional 53:47 D-T fuel mix. By spin-polarizing half of the fuel and adjusting the mixture to 60:40 D-T, this requirement dropped to just 0.08 kg. Further improvements, including fully spin-polarizing the fuel with a 63:37 D-T mix, reduced the inventory to a mere 0.03 kg. Parisi notes, “Some ARC-like scenarios are predicted to achieve plasma ignition with relatively modest spin polarization,” underscoring the potential for practical applications in fusion energy.
The implications for the energy sector are profound. By significantly lowering the tritium startup inventory requirements, this research could reduce the need for on-site tritium, which is both costly and logistically challenging. As the industry moves closer to viable fusion energy, advancements in helium divertor pumping efficiency could lead to TBE values of around 10%–40%, representing a substantial leap in performance.
This research not only paves the way for more efficient fusion reactors but also opens up commercial opportunities in the energy sector, particularly in the development of advanced fuel cycles and technologies that leverage spin-polarized fuels. As the world seeks cleaner, sustainable energy sources, the findings from Parisi and his team could play a crucial role in the future of fusion energy.
For more information on the research, visit the Princeton Plasma Physics Laboratory.
