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Europe follows fusion twin track

7 October 08 03:57 GMT
By Jonathan Amos
Science reporter, BBC News

An alternative fusion project has been kicked off in Europe that would seek abundant clean energy using a colossal laser the size of a football stadium.

The laser would tap the energy by squeezing together atoms of hydrogen - a process very similar to the one that powers the Sun.

Europe is already engaged in the Iter fusion venture that aims for the same outcome but via magnetic confinement.

The Hiper programme is seen as a necessary complementary route.

"We have two approaches because of the prize that is out there; fusion energy is the holy grail of energy sources," said Hiper project leader Professor Mike Dunne.

"It offers energy security because the fuel comes from seawater; it offers abundant supply, it's clean and it's safe. So the prize is huge and we believe we need as many approaches as possible to make that prize a reality," he told BBC News.

'Spark plug'

The technical challenge of making fusion happen, however, is huge; and a viable solution has eluded scientists for 50 years.

The Hiper (High Power Laser Energy Research) study has been instigated by the European Commission and involves the participation of 26 institutions from 10 countries. Keys players are the UK, the Czech Republic and France.

The intention is to establish the practicalities of building an experimental facility to demonstrate so-called Inertially Confined Fusion Energy.

This would see a high-powered laser-pulse compress a ball-bearing-sized pellet of "heavy" hydrogen - the atomic forms, or isotopes, known as deuterium and tritium - to achieve a density 30 times that of lead. A second pulse of light would then raise the temperature in the compressed pellet to more than 100 million Celsius.

In these conditions, the hydrogen nuclei would fuse to form helium. According to theory, a small amount of mass would be lost and a colossal amount of energy would be released.

"Think of it as a car engine," said Professor Dunne.

"First of all you inject the fuel and then in a car engine, a piston will compress the fuel. In our case, we use a big laser to compress our fusion fuel.

"Then, just like in a car engine, you have a spark plug that lights the fuel. We also use a spark but in our case, we use another laser - a very high-powered, very short-pulsed laser. You then exhaust the products and repeat the cycle again, and again, and again - just like in your car engine."

Doughnut approach

The "proof of principle" of laser fusion is anticipated in the next few years based on two very large-scale lasers currently nearing completion - at the National Ignition Facility in California, US, and at Laser Megajoule in Bordeaux, France.

It is hoped these facilities will show in single experimental events that more energy can be got out of the process than is required to initiate it.

Hiper's role will be to demonstrate the technical practicalities of exploiting the principle, of turning those single events into a continuous cycle that will make commercial power plants are reality.

Last week, the legal documentation was signed to start the current phase of Hiper. It is being funded with 13m euros of hard cash and approximately 50m euros of what is termed in-kind assistance - the provision of hardware and expertise from member parties.

Assuming all goes well, the feasibility study will be followed by a period of prototyping, leading to the building of a demonstration unit towards the end of the next decade.

The timescales involved are not dissimilar to the other type of fusion now being pursued by the International Thermonuclear Experimental Reactor, or Iter, under construction at Cadarache in France.

It will try to initiate fusion in a super-heated volume of gas constrained by magnetic fields in a doughnut-shaped vessel.

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