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View Full Version : Northern Lights' Physics Could Aid in Nuclear Fusion



skywizard
7th May 2014, 14:25
http://i.livescience.com/images/i/000/065/776/original/aurora-earth-140506.jpg?1399387530
A view of the aurora australis as taken by the Imager for Magnetopause-to-Aurora Global
Exploration (IMAGE) spacecraft.



The aurora is more than just a breathtaking display of light. It may also hold the secret of a magnetic phenomenon related to the nuclear fusion powering the sun. This secret could even help create nuclear fusion in the lab, says a team of researchers.

Nuclear fusion is a reaction that combines the nuclei of two atoms into one. The process powers stars, but getting a self-sustained fusion reaction going on Earth is very difficult, and has so far eluded scientists. For example, in February, researchers at the Lawrence Livermore Laboratory in California made headlines when they managed to spur a fusion reaction that ate up less fuel than it produced. But the overall process of triggering the reaction still took more energy than was generated.

Now a team of researchers from the University of Michigan and Princeton University hopes that the performance of fusion experiments can be improved by investigating of the dynamics of magnetic fields observed during the aurora.

Elusive fusion

To trigger a fusion reaction on Earth, one must compress the fuel (typically equal mixtures of deuterium and tritium, which are two isotopes of the hydrogen atom) to a temperature and density similar to that at the core of a star. If the hydrogen fuel is held long enough under these very specific conditions, the superheated gas turns into a "soup" of freely moving, charged particles called plasma. In this state, the hydrogen starts fusing into energetic helium. That’s how young stars burn, using hydrogen compressed by the stars' own gravity. As fusion devices become bigger and the plasma in them gets hotter and more compressed, there is hope to one day reach "ignition" — the point at which the plasma heats itself without external input.

Another galactic process might help usher along the quest for Earth-bound fusion. As the sun's plasma swirls around, the substance generates a strong magnetic field. Sometimes, this field is so highly stressed that its field lines are forced together, at which point the Sun releases a huge amount of energy into space, known as a solar flare. At times, the flare explodes straight in the direction of Earth, sending a stream of highly charged solar particles to the planet.

When the solar particles approach Earth, they distort its magnetic field, which allows some charged particles to enter the atmosphere at the North and South Poles. As the particles interact with gases in the Earth's atmosphere, those gases begin to glow. In the north, this is known as aurora borealis, or the Northern Lights. The Southern Lights, seen in the Southern Hemisphere, are called aurora australis.

If this solar wind is especially strong, it can cause the planet's magnetic field lines to disconnect from Earth. Then, after moving about a third of the way from the Earth to the moon, these lines reconnect and snap back into position. In the process, they sling charged solar particles toward the Earth's atmosphere, triggering the aurora. This breaking and reconnecting of oppositely directed magnetic field lines is called magnetic reconnection. Incidentally, scientists also believe that magnetic reconnection powers the solar flares themselves.

With the aurora borealis, for example, the northern lights usually occur near the North Pole, but the more the magnetic field lines disconnect and snap back, the further south the lights can appear.

However, magnetic reconnection also happens on a much smaller scale during nuclear fusion in the lab. And it is this process that could help make nuclear fusion energy-efficient, researchers reported on March 14 in the journal Physical Review Letters.



Read Full Story: http://www.livescience.com/45384-nuclear-fusion-aurora.html



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