JET design, construction and performance

The Joint European Torus (JET), is the largest tokamak experiment in the world and it represents the leading experiment of the European Community's Fusion Research Programme which is aimed at harnessing fusion energy for large scale electric power production. Its objective is to study plasmas of hydrogen isotopes, in reactor-relevant conditions. JET has been in operation since 1983 and can now operate at plasma currents of 7 MA, in a plasma volume well in excess of 100 m3 and with a toroidal magnetic field of 3.45 T. Moreover, it can operate with plasma currents up to 5 MA, in the very favourable magnetic limiter (X-point) configuration. Key JET technical features are D-shaped toroidal magnetic field coils and a D-shaped vacuum vessel, to allow plasmas of elongated cross-section to be produced and controlled. The plasma is heated by neutral injection and radio frequency. JET operates in pulses (up to 20 s long at full performance) every ten minutes and it requires pulses of electrical energy above 1000 MW, partly taken directly from the British supergrid and partly provided by two flywheel generators. The JET machine and its auxiliary facilities are described in the Paper. (author)