deuteriumHelium3

Deuterium–helium-3 fusion, abbreviated as D–He-3 fusion, refers to the fusion of a deuterium nucleus with a helium-3 nucleus to produce helium-4 and a proton, releasing a large amount of energy. The dominant fusion channel is d + He-3 → He-4 + p, with a Q-value of about 18.3 MeV.

In most treatments, the reaction products carry the energy that is released. Energetically, the proton receives the majority of the kinetic energy (roughly 14–15 MeV) while the helium-4 (alpha) particle receives a smaller share (a few MeV). The energy is primarily in charged particles, which has implications for energy capture and shielding.

Fuel availability and practical considerations are major factors. Deuterium is abundant in seawater, but helium-3 is relatively scarce on Earth, making terrestrial supply a significant challenge. Potential sources of helium-3 discussed in the literature include extraterrestrial reservoirs and specialized production methods, but the material cost and sourcing remain substantial barriers to widespread use.

Technological prospects and challenges are driven by its aneutronic nature. The main reaction produces no neutrons, offering advantages for reduced radioactive activation and the possibility of direct energy conversion from charged particles. However, the D–He-3 cross-section at practical fusion temperatures is smaller than that of the more studied deuterium–tritium cycle, requiring higher temperatures or alternative confinement approaches. Additionally, obtaining sufficient He-3 and achieving net energy gain remain major hurdles.

As a result, D–He-3 fusion is a topic of interest in theoretical and experimental fusion research, particularly for its potential to enable cleaner, direct-energy fusion, but it has not yet progressed to a practical power source.