【核融合】中性子を生成しない熱核融合反応を起こす方法

A technique for driving thermonuclear fusion reactions that release energy without producing hazardous high-energy neutrons is reported in Nature Communications this week. The approach could enable researchers to study a wider range of the sorts of nuclear reactions that take place in stars, and to explore new fuels for fusion-based power generation.

Nuclear fusion involves the combination of light atomic nuclei at immense temperature and pressure to produce heavier atomic nuclei. This process produces large amounts of energy and could provide a source of essentially limitless electrical power. But there are many challenges in trying to harness this process. One such challenge is the fact that the reaction of deuterium and tritium nuclei - whose conditions are within the closest reach of current technology - produce high-energy neutrons. Containing them requires heavy shielding around the core of a fusion reactor, and causes the walls themselves to become radioactive.

Christine Labaune and colleagues demonstrate a technique for fusing hydrogen and boron-11 nuclei - a reaction that produces beryllium-8 and alpha particles (helium nuclei) but no neutrons. They find that when they drive a short burst of laser-driven protons (hydrogen nuclei) into a laser-generated plasma of boron ions, they detect the emission alpha particles at energies consistent with the fusion of the two species but without creating potentially problematic neutrons.

The reaction rate the authors infer from their results is more than ten times greater than previously reported for this particular reaction. Although this is still far below that needed for power generation, the authors believe it should be useful for studying this and other reactions, in the development of new nuclear fuels and new approaches to fusion. It could also help us better understand the many different nuclear reactions that take place in the cores of stars.