JET is an experimental fusion facility based at Culham Science Centre. It is the only machine currently operating in the world that can use the deuterium/tritium fuel that will be used in the prototype fusion reactor ITER.

As UKAEA's Fusion Programme Manager at Culham Science Centre Martin O'Brien is well aware of the research challenges that must be met for fusion to become a commercial proposition. While the first prototype fusion power stations may be generating electricity in 30 years time, he believes it will be another decade after that before commercial fusion comes on-line. Why the wait? Think of it like this: the researchers are essentially trying to replicate what happens inside the sun here on earth. This involves creating and sustaining a super-hot plasma – an ionised 'soup' of nuclei and electrons – unlike anything else on the planet. The history of fusion research at Culham is the history of experimenting with bigger and hotter plasmas in different types of experimental machines. Culham's programme is conducted within the framework of a pan-European programme: It currently hosts the fusion facility JET (Joint European Torus). "JET still holds the world record for fusion power at 16 megawatt achieved in 1997," Mr O’Brien tells us, "the experiment has also come close to achieving 'break-even', with the fusion power equalling the power needed to keep the fusion gas (or plasma) hot enough for fusion to occur." Another world-leading facility operated at Culham is a 'spherical tokamak' called MAST. In the long-term spherical tokamaks could be the basis for more compact fusion power stations.

Artist’s impression of how the new ITER facility will look when it is built at Cadarache, France.

The next step towards commercial fusion is the prototype ITER reactor. After protracted debate the decision to build ITER in Europe was taken in 2005. However JET, which is funded by EU partners including EPSRC, and MAST will have plenty to do in the ten years while ITER is being built. "JET is the only machine operating currently in the world that can use the deuterium/tritium fuel that will be used in ITER, the intention is to upgrade JET's heating and to change the material of the inner wall of the machine from carbon-composite tiles to the beryllium tiles planned for ITER," Mr O'Brien explains. "MAST will continue to provide information on whether the spherical tokamak will prove a good, more economic option for fusion reactors, whilst carrying out ITER-related work," he adds.

The MAST experimental machine may help researchers design more compact fusion reactors.