JET sets fusion energy record

Scientists in Oxfordshire have set a new world record for the amount of energy produced by nuclear fusion, the process that powers the Sun.

The Joint European Torus, known as JET, produced 59 megajoules of energy over five seconds, more than double the previous record set in 1997. The result was announced on 9 February.

What is fusion?

Nuclear fusion involves forcing the nuclei of light atoms, such as forms of hydrogen, together so that they fuse and release huge amounts of energy.

It is the opposite of nuclear fission, used in today's nuclear power stations, which splits heavy atoms. Fusion produces no greenhouse gases and much less long-lived radioactive waste.

But achieving fusion on Earth is extremely difficult. The fuel must be heated to temperatures ten times hotter than the centre of the Sun, and held in place by powerful magnetic fields.

The experiment

JET, based at the Culham Centre for Fusion Energy near Abingdon, is a doughnut-shaped machine called a tokamak. It has been operating since 1983 and is the largest working fusion experiment in the world.

The record was set using a mixture of deuterium and tritium, two forms of hydrogen, which will be the fuel for future fusion power stations.

The energy produced is roughly enough to boil around 60 kettles of water. The machine still uses far more energy to heat the fuel than it produces.

A step towards ITER

The experiment was designed to test materials and techniques for ITER, a much larger fusion reactor being built in southern France by an international partnership. ITER aims to produce ten times more energy than it takes to run.

Britain's role

JET is run by the UK Atomic Energy Authority on behalf of scientists from across Europe. The Science Minister, George Freeman, said the results showed Britain's leading role in fusion research.

The government is also developing plans for a prototype fusion power plant called STEP, to be built in Britain by the 2040s.

The future of JET

JET is due to close next year after four decades of experiments. Its future had been uncertain because of Britain's departure from the European Union.

Scientists say fusion power could one day provide almost limitless clean energy, but most believe it will be decades before it is commercially available.