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The Tokamak

Problems with early power plants led to the development of the Tokamak. An old design, known as the linear pinch method, suffered from large energy losses at the ends of the plant and macroscopic plasma instabilities. To overcome these problems, a new design was developed by Russian scientists that added a strong magnetic field to "stiffen" the plasma. The new machine was called a Tokamak; a Russian acronym made from the first syllables of the words torid kamera (chamber), magnit (magnet) and the first letter of katushka (coil). The Tokamak consists of a series of superconducting magnet coils around a toroidal vessel that confine and control plasma and induce an electrical current through. Fusion is created when the plasma is hot and dense enough, and is confined long enough for the atoms to fuse together. In 1968, the T-3 Tokamak had an energy confinement time of only several milliseconds, but this was still much larger than anything that had been developed prior.

An artist's sketch of a Tokamak reactor.

A picture from the inside of a Tokamak.

Other Tokamaks were built around the world, and after some effort, the Soviet's results were duplicated. Larger Tokamaks were also constructed, such as the Soviet T-10 and the PLT in the United States.
In later versions of the Tokamak (the TFTR in the US, the T-15 in the USSR, JET in Europe, and JT-60 in Japan), additional heating power (in the form of powerful neutral beams) was injected into tokamaks to raise the plasma temperature. The current Tokamak in US production is the ITER. The ITER will be twice as large as existing designs, and much larger fusion reactions are expected. For a detailed schematic of ITER, go to You can also try out an interactive Tokamak at

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