Fusion power is the power generated by nuclear fusion reactions. In this kind of reaction, two light atomic nuclei fuse together to form a heavier nucleus and in doing so, release a large amount of energy. In a more general sense, the term can also refer to the production of net usable power from a fusion source, similar to the usage of the term "steam power." Most design studies for fusion power plants involve using the fusion reactions to create heat, which is then used to operate a steam turbine, which drives generators to produce electricity. Except for the use of a thermonuclear heat source, this is similar to most coal-fired power stations and fission-driven nuclear power stations.
The largest current experiment is the Joint European Torus (JET). In 1997, JET produced a peak of 16.1 MW of fusion power (65% of input power), with fusion power of over 10 MW sustained for over 0.5 sec. In June 2005, the construction of the experimental reactor ITER, designed to produce several times more fusion power than the power put into the plasma over many minutes, was announced. They are currently preparing the site (Sep 2008). The production of net electrical power from fusion is planned for DEMO, the next generation experiment after ITER. Additionally, the High Power laser Energy Research facility (HiPER) is undergoing preliminary design for possible construction in the European Union starting around 2010.