Laser vision fuels energy future...

Laser vision fuels energy future Read the full article here from BBC


Nuclear fusion has long been a dream of scientists. The idea is to fuse together two heavier forms of hydrogen, known as deuterium and tritium, to form helium.

These isotopes of hydrogen are readily available.

"In just one cubic kilometre of seawater there is the equivalent energy of the world's oil reserves," says Professor Dunne. "So it's almost limitless fuel."



LASER FUSION


1. Powerful lasers irradiate a fuel capsule causing the outer layer to rapidly expand.
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When the isotopes are combined at high temperatures, a small amount of mass is lost and a colossal amount of energy is released. By-products are no more radioactive than hospital waste.

In the core of the Sun, huge gravitational pressure allows this to happen at temperatures of around 10 million Celsius. At the much lower pressures on Earth, temperatures to produce fusion need to be much higher - above 100 million Celsius.

Hiper would achieve these extreme temperatures using ultra powerful lasers - some will concentrate the equivalent of ten thousand times the power of the national grid into a spot less than a millimetre across.

The whole scheme has been drawn up to capitalise on a US project at the National Ignition Facility (NIF) at the Lawrence Livermore National Laboratory in California.

Scheduled for completion in 2010, the massive NIF laser is expected to prove to the world that laser fusion will work and should be taken seriously.

"That will move it from the scientific field to the public and political field," says Professor Dunne.

"Everything from then on is just mere detail - it's technology and engineering."

Commercial reality

The NIF laser and Hiper take very different approaches to laser fusion. Professor Dunne compares it to the differences between a diesel and petrol engine.

"Nif is the diesel approach," he says. "You shine lasers at a pellet of material and compress it to such a point that its temperature and density reach a point that allows fusion reactions."



It sounds like a lot of money, but in the greater scheme of things, half a billion dollars to solve the world's energy problems is nothing

Mike Dunne




In contrast, Hiper will use two sets of lasers: one to compress the fuel pellet and another, like a spark plug, to ignite it. Using this set up means that the fuel does not need to be compressed as much as it does with NIF, overcoming a major hurdle.

"It's like trying to squeeze jelly," explains Professor Bob Bingham, also of the RAL. "You want to squeeze in a way that it doesn't come back out through your fingers. That really is the key."

Nif engineers get round this problem by using ultra precise lasers and near-perfect shaped fuel pellets, both of which are delicate, time consuming and unlikely to be ever viable routes to a commercial reactor.

Using the secondary laser, a technique first demonstrated by Japanese scientists, means the machinery of Hiper can be a bit more rough and ready.

Small cost

But the Hiper team will not have it all its own way.