German plasma success raises nuclear fusion hopes

A German nuclear fusion experiment has produced a special super-hot gas which scientists hope will eventually lead to clean, cheap energy.
The helium plasma - a cloud of loose, charged particles - lasted just a tenth of a second and was about one million degrees Celsius.
It was hailed as a breakthrough for the Max Planck Institute's stellarator - a chamber whose design differs from the tokamak fusion devices used elsewhere.
The Sun's energy is created by fusion.
Physicists are in a worldwide race to create stable fusion devices that could not only mimic the Sun but release abundant energy, without the volumes of toxic waste generated by nuclear fission - the splitting of the atom.

The team at Greifswald, in northeastern Germany, aim in future to heat hydrogen nuclei to about 100 million C - the necessary conditions for fusion to take place like in the Sun's interior. They will use deuterium, a heavier type, or isotope, of the element.

The stellarator's plasma was created on Thursday using a microwave laser, a complex combination of magnets and just 10mg of helium. The Max Planck Institute calls its machine Wendelstein 7-X.

The project began nine years ago and has cost 1bn euros (£720m; $1.1bn) so far.

The EU's main nuclear fusion project is called Iter, at Cadarache, in the south of France. But it will not be fired up until the 2020s. It is controversial, having already cost more than €10bn.

Iter will be a tokamak device - the word comes from Russian, meaning a ring-shaped magnetic chamber.

Scientists have been working on nuclear fusion for more than 50 years but the extreme temperatures involved and the difficulty of controlling plasmas mean progress is slow.