The compression produces immense pressure and temperature, leading to a fusion reaction. Problems with the process were overcome last September, when, for the first time, Hurricane was able to produce more energy output from a fusion reaction than the lasers put into it. Since then, he has been able to repeat the experiment.
Hurricane’s current output, although more than the hydrogen fuel put into the reaction, hasn’t yet reached the stated goal to achieve “ignition,” where nuclear fusion generates as much energy as the lasers supply. At that point it might be possible to make a sustainable power plant based on the technology.
In plasma physics, the energy produced by a fusion reaction increases exponentially with the pressure applied to the system. According to Hurricane, they only need to double the pressure to achieve ignition. His other achievement is that, with these experiments, he has been able to show that computer simulations can predict experimental results.
Scientists have been trying to tame fusion power for more than 50 years with little success. Although the National Ignition Facility, a $3.5-billion operation, was built for classified government research, half of its laser time was devoted to fusion with an aim to accelerate research. Zulfikar Najmudin, a plasma physicist at Imperial College, said: “These results will come as a huge relief to scientists at NIF, who were very sure they could have achieved this a few years ago.”
With laser-mediated ICF showing positive results, the obvious question is how does it compare with magnet-mediated fusion? According to Stephen Cowley, director of Culham Centre for Fusion Energy, there isn’t a precise way of comparing the two technologies. But if a comparison has to be made, MCF still is ahead of ICF because a 1997 experiment by the European fusion leaders Joint European Torus achieved near break-even when they produced 16MW (megawatt) of energy for 24MW of input.
“We have waited 60 years to get close to controlled fusion. We are now close in both magnetic and inertial. The engineering milestone is when the whole plant produces more energy than it consumes,” Cowley said. That may happen at the fusion reactor ITER, under construction in France, which is expected to be the first power plant that produces more energy than it consumes to sustain a fusion reaction.
Nature, 2014. DOI: 10.1038/nature13008 (About DOIs).
This article was originally published on The Conversation.
Update: The post was corrected to clarify that experiment produced more energy than was needed to kickstart the fusion reaction.