Science

Nuclear fusion a step closer

Exciting results are emerging from the National Ignition Facility (NIF) in California. This facility, tasked with the aim of creating nuclear fusion from a small target of hydrogen isotopes by blasting them with a massive laser, has finally seen some encouraging results.

The five-year-old facility in California has had a turbulent history. When the facility failed to produce encouraging results in its first three years, the American Congress granted it a three year extension. Its aim is nuclear fusion, the process whereby more energy is released from the system than is used to start it. Nuclear fusion powers our Sun and is instrumental if our ever-increasing energy needs are to be met cleanly and efficiently in the future.

NIF has produced a blast of energy ten times bigger than ever before and has been able to demonstrate the phenomenon of self heating, an important first step to the ever elusive ignition of fusion.

“This is a very significant achievement, and it’s a very good place to start for going to higher yield” says Steven Rose of the Centre for Inertial Fusion Studies at Imperial Collage London.

The new results, published in  Nature, are encouraging, but NIF has a long way to go before it’s reached its aim. Scientists have been tweaking the laser beam to hit its small hydrogen target with higher power but at a shorter amount of time, just 15 nanoseconds in a process dubbed “hot foot”.

It was thought that this methodology wouldn’t produce encouraging results, since the hydrogen target wouldn’t reach the high densities observed in the normal laser beam bursts. The scientists were surprised, however, to observe that by using this “hot foot” method, self-heating of the hydrogen target was observed.

This experimental data started to agree more and more with simulated data, with NIF director Michael Campbell stating “Doing these less-demanding implosions, results now agree with the codes and that’s very exciting”.

Some have their doubts, however, such as Robert McCrory, director of the Laboratory for Laser Energetics in New York, who said: “They’re pushing about as far as they can go”. Despite these doubts, NIF researchers remain confident by their renewed progress and they are hopeful the ever-elusive nuclear fusion is just around the corner.

Scott Davies

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