Smaller fusion reactors could deliver big gains

Researchers from the UK firm Tokamak Energy say that future fusion reactors could be made much smaller than previously envisaged – yet still deliver the same energy output. That claim is based on calculations showing that the fusion power gain – a measure of the ratio of the power from a fusion reactor to the power required to maintain the plasma in steady state – does not depend strongly on the size of the reactor. The company's finding goes against conventional thinking, which says that a large power output is only possible by building bigger fusion reactors.