Self-sustaining aneutronic beryllium–helium-3 cycle with proton management

Determine how to manage the approximately 15 MeV protons produced in the secondary deuterium–helium-3 reaction and identify an additional target component capable of multiplying or redistributing those protons at suitable energies so that the proton–beryllium–helium-3 cycle can close efficiently.

Background

The proposed cycle uses a proton beam and a target mixture of 9{}^{9}Be and 3{}^{3}He. Proton capture on 9{}^{9}Be produces a deuteron, which can resonantly fuse with 3{}^{3}He and regenerate a proton, suggesting a potentially aneutronic and self-sustaining cycle. The secondary reaction also produces a high-energy proton whose energy and multiplicity are not yet suitably integrated into the cycle, creating a concrete unresolved design problem.

References

Of course there are unsolved problems: we have a relatively high energy 15 MeV proton produced in the secondary $d+{}{3}\mathrm{He}$ reaction. It is very desirable to add another component to the ${}9\mathrm{Be}$, ${}{3}\mathrm{He}$ target allowing protons to be multiplied, `splitting' energy so that the cycle closing reaction would benefit from several protons at convenient energy.

— Science Of Nuclear Fusion: Insights and Ideas  (2609.01366 - Rafelski et al., 1 Sep 2026) in Section 3, subsection “Nuclear Fusion Everywhere,” subsection “Beryllium based aneutronic fusion cycle,” paragraph “Beryllium–${}^{3}$He fusion chain”