Fusion experiments at the Joint European Torus (JET) fusion project in Oxfordshire, UK, are more than halfway to breakeven – the point where the power produced by the reactor equals that supplied to it. But a decision on whether the experiments should continue after 1999 has yet to be taken.

For the last six weeks, JET has been using a 50:50 mix of deuterium and tritium fuel. When the fuel is confined inside a torus by strong magnetic fields and heated to extremely high temperatures to form a plasma, the deuterium and tritium nuclei fuse to form a helium nucleus and a neutron. A small amount of mass that is lost in the reaction is converted into energy. On 22 September, JET set a new world record for fusion by achieving a 12.9 MW output – 60% of the input power. The experiments continued as Physics World went to press. “We hope to get more power, ” says Martin Keilhacker, director of JET.