[en] Fusion, the nuclear engine that powers the sun and stars, has been pursued by scientists for decades as the ultimate source of energy. It promises an almost inexhaustible fuel supply with the oceans containing sufficient fusion fuel to outlast the expected life of the sun. Fusion is a process whose waste is inert and whose components know no geographical bounds. Scientists have pondered the laws governing the fusion process since the 1940's, and since the late 1950's laboratory devices have been constructed to test and further develop the theories. To achieve fusion, the joining of light atomic nuclei (as opposed to the splitting of heavy elements in the fission process), the natural tendency of the nuclei to repel each other due to their like electrical charges must be overcome. As the fusion takes place, some of the matter of the nuclei is converted to energy. In the stars fusion is accomplished largely by enormous gravitational forces. On earth the fusion fuel must be heated by other means to increase the energy of the particles to force them to fuse. Therein lies the challenge of fusion research - how to heat sufficient matter to hundreds of millions of degrees and contain it long enough for a controlled and sustained fusion reaction to take place. The method that presently shows the most promise is to contain a plasma (an ionized gas - the fourth state of matter) in a magnetic field while heating the plasma by means of high energy neutral particle beams or radio frequency waves