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Last Updated: Tuesday, 11 November, 2003, 15:10 GMT
Solar flare 'reproduced' in lab
By Dr David Whitehouse
BBC News Online science editor

A man-made solar flare
Plasma dances in the lab just like on the Sun
Scientists have simulated a solar flare in the lab, recreating the super-heated cloud of electrically-charged gas seen on the Sun known as a plasma.

It was part of an initiative to develop fusion power - the nuclear energy that keeps the Sun shining.

The plasma in the lab behaved like a miniature version of a solar flare.

Scientists hope they can create a flare at low energies in the lab, to enable them to study the explosive events that take place on the Sun's surface.

Magnetic bottle

The work was carried out at the Culham Science Centre near Oxford, by scientists working on the Mega Amp Spherical Tokomak (Mast) project.

A tokomak is a magnetic bottle designed to confine a plasma - super-heated electrically charged ionised gas.

The tokomak was invented by the Russians. In it, two magnetic fields are combined to hold the plasma.

Mast fusion chamber
Plasma filaments like the Sun but in the lab
The world's largest tokamak is called Jet, the Joint European Torus. It is also at Culham.

Using Jet, scientists have heated plasma to 300 million degrees - more than is needed to achieve fusion ignition. But magnetic confinement is easier if the plasma is kept small.

Mast keeps the plasma in a tighter configuration that is more energy efficient.

Solar flare secrets

The scientists were interested in a phenomenon called edge-localised modes (ELM) - a particular instability that can form in a plasma.

Understanding ELMs is important for the design of future fusion reactors.

The researchers believe that when the plasma reaches a certain critical instability, ELMs form.

Mast fusion chamber
The chamber that confines a man-made sun
They also realised that ELMs, like solar flares, are explosive events, which can eject particles and energy.

Using Mast the researchers have carried out new measurements of ELMs, obtaining unprecedented detailed images of filamentary structures associated with them.

The filaments immediately reminded them of the huge plasma structures that loop over the Sun's surface.

Culham's Andrew Kirk said: "The similarities were striking. They looked like the filaments seen in detailed images of the Sun."

The real thing
The real thing is far bigger and more powerful
Co-researcher Howard Wilson was interested in the size of the filaments.

"Although Mast is only a few metres in size and the Sun over a million kilometres in size, when the physics of the plasma is taken into account the filaments seen in Mast and on the Sun are roughly the same size when measured relative to the gas that spawned them."

This means that the secrets of solar flares may be right in front of the scientists.

Rob Akers of Culham told BBC News Online: "We may be seeing a solar flare in miniature, taking place in the laboratory. Being able to study it in detail will help us understand what's going on at the Sun, where the plasma clouds are bigger and the energies greater."




SEE ALSO:
Fusion power 'within reach'
01 Oct 01  |  Science/Nature
Alternative fusion machine limbers up
08 Apr 03  |  Science/Nature
US and China join fusion project
25 Feb 03  |  Science/Nature


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