MAST - Background information

The EURATOM/UKAEA Fusion Association has constructed a new fusion machine at Culham. The new tokamak, called MAST (Mega Amp Spherical Tokamak) has taken over from the highly successful existing machine of this type at Culham, START (Small Tight Aspect Ratio Tokamak), which completed its experimental programme in March 1998.

The new machine took two years to design and a further two years to construct. It has been fully commissioned and the experimental programme commenced in December 1999. Components for MAST were manufactured by many European industrial firms (see list) and assembled within an existing building at UKAEA Culham, Oxfordshire.

The motivation for building MAST was the outstanding success of it's forerunner, START. START’s performance has exceeded even the most optimistic predictions, and results showed that spherical tokamaks may have a number of advantages over the more conventional design in the search for economic power from fusion. However, it is recognised that this research is still in its early stages and results need to be confirmed and extended on a much larger purpose-built device. This, as well as increasing our understanding of how tokamaks work, is the reason for building MAST and therefore ensures that the EURATOM/UKAEA programme continues to be at the forefront of this branch of fusion research.

Machines like MAST and START differ from ordinary tokamaks in the shape in which the plasma (a hot ionised gas) is held by magnetic fields. In a conventional tokamak the plasma is held in a toroidal configuration, rather like a car tyre or doughnut. In a ‘spherical tokamak’ such as MAST the plasma shape, though still toroidal, is much more compact, something like a cored apple. It is almost spherical, hence the name.

Back to MAST home page