Research press release


Nature Communications

Nuclear fusion: Yes, we have no neutrons



今回、Christine Labauneたちは、水素とボロン11の原子核を融合する1つの方法を実証した。この核融合反応は、ベリリウム8とアルファ粒子(ヘリウム原子核)を生成するが、中性子を生成しないのだ。つまり、Labauneたちが、レーザーで生成されたボロンイオンのプラズマにレーザー駆動の陽子(水素原子核)の短く強力なビームを衝突させたところ、アルファ粒子が放出されたが、問題を起こす可能性のある中性子は生成されなかった。そして、そのアルファ粒子のエネルギーは、水素とボロン11の原子核融合によって放出されるエネルギーに匹敵することが検出された。


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.

doi: 10.1038/ncomms3506


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