fusion, nuclear

fusion, nuclear Form of nuclear reaction in which nuclei of light atoms (such as hydrogen) combine to form one or more heavier nuclei with the release of large amounts of energy. The process takes place in the Sun and other stars, and has been reproduced on Earth in the hydrogen bomb. Efforts have since been concentrated on producing controlled fusion reaction in a thermonuclear reactor. Two main methods have been employed. In the first, a plasma of tritium and deuterium is raised to a temperature above 100 million°C in a tokamak reactor. The second method is laser fusion, in which a laser implodes a pellet of tritium and deuterium. At present, both methods fail to produce more energy from fusion than is put into the system. See also fission, nuclear; nuclear energy