1 Government shutdown slows news of fusion breakthrough on Sat Nov 30, 2013 9:12 pm
Producing power like the sun? We're getting closer.
Credit: NASA's Solar Dynamics Observatory
The possibility of fusion-based power plants, long a dream of science and science fiction, is getting closer to reality. Fusion, the self-sustaining reaction of high-speed collisions between atoms (well, really, their nuclei) that makes the Sun the Sun, could provide cheap and unlimited energy—that is, if we could only get a reaction started that produces more energy than it needs to get going.
This has been the hard part, but a team of researchers at the National Ignition Facility (NIF), part of the Lawrence Livermore National Laboratory, has been using the world's most powerful targeted laser system to try to figure it out. The holy grail they are seeking is ignition—the point where the fusion reaction becomes self-sustaining under the conditions above.
Yesterday, the BBC reported that researchers at NIF created a fusion reaction where the energy produced was more than the energy absorbed by the fuel. That's a huge breakthrough, but it's still not as much energy as the lasers that provide the energy were putting in. Some energy in the system is being lost in the process' inefficiencies. So that makes the attempt pretty close but not quite to that ignition point.
When Ars reached a spokesman with the NIF to verify this story, he said he was unable to comment at this time. As federally funded researchers, they have likely been furloughed.
What we know for sure is that in late August, the lab released news of a major breakthrough and followed up with a paper in September. They blasted a tiny capsule containing two hydrogen isotopes, deuterium and tritium, with 192 lasers which, with their powers combined, can provide 1.8 megajoules of energy in an instant.
Hit with the laser blast, the D-T pellet compresses and then explodes, creating 8,000 joules of neutron energy—three times more energy than they had ever produced before. Analysis to understand exactly what happened (and how) is still underway, but "early calculations show that fusion reactions in the hot plasma started to self-heat the burning core," according to the press release. This is getting close to the boundary where the fusion reaction takes over the process.
In the press release, associate director for the NIF Ed Moses said, "The yield was significantly greater than the energy deposited in the hot spot by the implosion. This represents an important advance in establishing a self-sustaining burning target, the next critical step on the path to fusion ignition."
Maybe in finishing those calculations, researchers reached the conclusion that the BBC published: energy absorbed was exceeded by the energy produced, meaning they are tantalizingly close to crossing that key ignition boundary. Unfortunately, we'll have to wait until Congress gets its act together to learn more.]