Nuclear fusion is a process in which two or more atomic nuclei combine to form one or more different atomic nuclei and subatomic particles. The process releases a massive amount of energy because the total mass of the resulting single nucleus is less than the mass of the two original nuclei. The fusion reaction powers the Sun and other stars. In order for fusion to occur, two light atomic nuclei, usually deuterium and tritium, need to collide with each other at extremely high temperatures, around ten million degrees Celsius. The high temperature provides them with enough energy to overcome their mutual electrical repulsion. Once the nuclei come within a very close range of each other, the attractive nuclear force between them will outweigh the electrical repulsion and allow them to fuse.
Key points about nuclear fusion include:
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Thermonuclear fusion: This is the process of atomic nuclei combining or "fusing" using high temperatures to drive them close enough together for this to become possible. Such temperatures cause the matter to become a plasma and, if confined, fusion reactions may occur due to collisions with extreme thermal kinetic energies of the particles.
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Deuterium-tritium fusion: This is the fusion reaction that researchers working on fusion energy applications are especially interested in. It produces a neutron and a helium nucleus and releases much more energy than most fusion reactions.
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Hybrid nuclear fusion: This is a proposed means of combining fusion and fission in which the blanket surrounding the core is a subcritical fission reactor. The fusion reaction acts as a source of neutrons for the surrounding blanket, where these neutrons are captured, resulting in fission reactions taking place. These fission reactions would also produce more neutrons, thereby assisting further fission reactions in the blanket.
Nuclear fusion is a promising source of energy production, but it is not yet a viable technology for use on Earth.
