A candidate aneutronic reaction between a proton and a boron-11 nucleus that yields three alpha particles and no primary neutrons, but demands extreme plasma conditions far beyond conventional D–T fusion.
The reaction proceeds through an intermediate excited state of carbon-12 which decays into beryllium-8 and an alpha particle; the unstable 8Be then promptly fissions into two more alpha particles. All products are charged, no neutrons produced in the primary channel.[1]
The p–11B reaction rate is far lower than D–T across all temperatures, peaking near 150–300 keV (roughly 1.5–3.5 billion °C). The energy released (8.7 MeV) is half that of D–T (17.6 MeV), and the higher nuclear charge of boron dramatically increases radiation losses.[1]
Rider (1997) showed that in a thermalised p–11B plasma, bremsstrahlung power exceeds fusion power at all temperatures, making net energy gain impossible under thermal-equilibrium assumptions without auxiliary energy recovery of the radiated X-rays.[2]
Proposals to circumvent Rider’s constraints include non-equilibrium plasma distributions, beam–target configurations, and laser-driven block ignition. Experiments have demonstrated p–11B fusion reactions using lasers, but yields remain many orders of magnitude below energy break-even.[3]
Proton–boron fusion is a claim of long-term promise rather than a verified path to energy production. No experiment has demonstrated Q > 1 or sustained burn in a p–11B plasma. The physics barriers are formidable and no clear solution has been validated.