A type of fusion reaction in which a single proton fuses with the nucleus of a boron atom to form three alpha particles. No neutrons are produced and therefore this type of reaction is referred to as aneutronic fusion. It is interesting from an energy point of view because it only generates charged helium nuclei and no neutrons to activate the chamber material. In addition, the charged particles can be used to generate electricity directly by electromagnetic induction. Some research facilities are therefore aiming to achieve proton-boron fusion, whose ignition temperature of 1.4 billion kelvin is, however, much higher than the ignition temperature of deuterium-tritium fusion. So far, proton-boron fusion has been experimentally achieved in 2023 on the Large Helical Device (LHD) stellarator by the combined injection of boron powder and high-energy neutral beams into the plasma core.