Demonstration of aneutronic p-11B reaction in a magnetic confinement device

Aneutronic fusion using commonly available fuel such as hydrogen and boron 11 ( ^11 B) is one of the most attractive potential energy sources. On the other hand, it requires 30 times higher temperature than deuterium–tritium fusion in a thermonuclear fusion reactor condition. Development of techniques to realize its potential for the experimental capability to produce proton-boron 11 (p- ^11 B) fusion in the magnetically confined fusion device using neutral beam injection is desired. Here we report clear experimental exploration and measurements of p- ^11 B fusion reactions supported by intense hydrogen beams and impurity powder dropper installed in the magnetic confinement plasma Large Helical Device. We measured a significant amount of fusion alpha particle emission using a custom designed alpha particle detector based on a passivated implanted planar silicon detector. Intense negative-ion-based hydrogen beam injectors created a large population of up to 160 keV energetic protons to react with the boron-injected plasma. The p- ^11 B alpha particles having MeV energy were measured with the alpha particle detector which gave a fusion rate in a good agreement with the global p- ^11 B alpha emission rate calculated based on classical confinement of energetic proton, using experimentally obtained plasma parameters.