Science | Lasers hold the key to clean energy

What seemed like a futile experiment, ongoing for over 60 years, may have finally revealed a viable solution to the world’s future energy requirements.

The process of nuclear fusion is a replication of the reaction which occurs at the centre of the sun, releasing huge amounts of energy and producing the heat that sustains the solar system.

Scientists at the Nuclear Ignition Facility (NIF) in America last week managed to sustain the conditions of this reaction, about 100 million Kelvin and pressure of 150 billion times atmospheric pressure, for around 1 billionth of a second and produce for the first time more energy than was put in.  The yield of around 14 kilojoules was not substantial on a human scale, however, should the reaction be sustained for longer, past the point known as ignition, the reaction would become self-sustaining.

Fusion is widely regarded as the best chance for clean energy that we have, possessing many advantages over the currently used technique of nuclear fission most noticeably the lack of radioactive waste and greater energy yields.

The fusion process used at the NIF involves using 192 high powered lasers to compress and fuse Deuterium and Tritium fuel capsules. At this point these isotopes of water shed the excess energy needed to maintain two atoms in relation to one atom.

Since 1997 scientists have been attempting this experiment using laser powered inertial confinement or magnetic confinement. Both systems require the compression of the two fuel capsules by a factor of 35, the equivalent of reducing a basketball to the size of a pea, while maintaining a perfect spherical shape. The two capsules must be then held no more than 10-15 meters from each other by the lasers or the magnetic fields with temperatures up to six times hotter than the centre of the sun before they can fuse together.

Fusion had been achieved previously, however, the input energies far exceeded the outputs; its only since NIF changed the pulse rates of the lasers that they managed to compress the capsules more efficiently and successfully which produced a far greater yield than before.

Off the back of this breakthrough the new ITER plant currently being built in France is expected to be the first plant to produce excess energy and provide a prototype for a viable nuclear fusion power station. Laser fusion provides the first real hope for unlimited clean energy.


Christopher Chadburn

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