The Small Tight Aspect Ratio Tokamak

Tokamak

A tokamak is a device using a magnetic field to confine a plasma in the shape of a torus . Achieving a stable plasma equilibrium requires magnetic field lines that move around the torus in a helical shape...

, or START was a nuclear fusion

Nuclear fusion

Nuclear fusion is the process by which two or more atomic nuclei join together, or "fuse", to form a single heavier nucleus. This is usually accompanied by the release or absorption of large quantities of energy...

 experiment that used magnetic confinement to hold plasma

Plasma (physics)

In physics and chemistry, plasma is a state of matter similar to gas in which a certain portion of the particles are ionized. Heating a gas may ionize its molecules or atoms , thus turning it into a plasma, which contains charged particles: positive ions and negative electrons or ions...

. The experiment began at the Culham Science Centre in the United Kingdom

United Kingdom

The United Kingdom of Great Britain and Northern IrelandIn the United Kingdom and Dependencies, other languages have been officially recognised as legitimate autochthonous languages under the European Charter for Regional or Minority Languages...

 in 1991 and was retired in 1998. It was built as a low cost design, largely using parts already available to the START team. The START experiment developed the tokamak by changing the previous toroid

Toroid

Toroid may refer to*Toroid , a doughnut-like solid whose surface is a torus.*Toroidal inductors and transformers which have wire windings on circular ring shaped magnetic cores.*Vortex ring, a toroidal flow in fluid mechanics....

al shape into a tighter, almost spherical, doughnut

Torus

In geometry, a torus is a surface of revolution generated by revolving a circle in three dimensional space about an axis coplanar with the circle...

 shape. The new shape increased efficiency by reducing the cost over the conventional design, whilst the field required to maintain a stable plasma was a factor of 10 less.

The START team holds the current highest record plasma pressure, which they achieved by using a neutral beam injector to heat the plasma. In March 1998, the START experiment finished and has since been disassembled and transferred to the ENEA

ENEA (Italy)

The L'Agenzia nazionale per le nuove tecnologie, l'energia e lo sviluppo economico sostenibile is an Italian Government sponsored research and development agency...

 research laboratory at Frascati

Frascati

Frascati is a town and comune in the province of Rome in the Lazio region of central Italy. It is located south-east of Rome, on the Alban Hills close to the ancient city of Tusculum. Frascati is closely associated with science, being the location of several international scientific...

, Italy

Italy

Italy , officially the Italian Republic languages]] under the European Charter for Regional or Minority Languages. In each of these, Italy's official name is as follows:;;;;;;;;), is a unitary parliamentary republic in South-Central Europe. To the north it borders France, Switzerland, Austria and...

. The START team began the Mega Ampere Spherical Tokamak

Mega Ampere Spherical Tokamak

The Mega Ampere Spherical Tokamak, or MAST experiment is a nuclear fusion experiment in operation at Culham, Oxfordshire, England since December 1999. It follows the highly successful START experiment...

Experiment or MAST in 1999 which still operates in the Culham Science Centre, UK.