Friday, February 14, 2014

Fusion Experiment Makes Breakthrough

Wired:
Scientists with the National Ignition Facility (NIF) at Lawrence Livermore National Laboratory announced today that they have achieved a critical step in fusion research: For the first time, their hydrogen fuel has given off more energy than it took in.
Though an important milestone, the result does not mean that your Delorean is soon going to sport aMr. Fusion reactor. NIF would need to sustain temperatures and pressures much greater than they are currently capable of before they can harness fusion energy.
Nuclear fusion is the energy source of the stars. Deep in our sun’s belly, hydrogen atoms slam into one another at high speed, getting mashed together to form helium atoms and releasing copious amounts of energy. Creating viable fusion energy here on Earth has been a dream since the dawn of the Atomic Age. With true fusion power, the amount of water you use in a single shower could provide all your energy needs for a year. But for six decades, fusion has remained a far-off dream.
To create fusion reactions at NIF, scientists shoot 192 lasers simultaneously with a peak power of 500 trillion Watts, roughly 1,000 times the power output of the U.S. grid. This heats up a 1 centimeter gold cylinder to millions of degrees, producing X-rays that get focused at a plastic shell the size of a BB pellet. The X-rays blast the shell, creating an implosion that shrinks the gas inside pellet to 1/35th of its size, compressing isotopes of hydrogen known as deuterium and tritium to incredible densities. At the center of this hydrogen plasma, in an area smaller than the width of a human hair, the atoms fuse. This gives off energy, which should in theory set off a chain reaction that ignites the rest of the hydrogen and creates a self-sustaining ball of fusion.
Because of this convoluted process, only 1/200th of the energy that the lasers generate is imparted to the hydrogen fuel, compressing it enough to produce a small amount of fusion. Until now, the energy given off by the fusing hydrogen hasn’t been enough to set off a chain reaction. The hydrogen fuel also always consumed more energy than it put out. But during experiments  late last year, NIF researchers were finally able to get the hydrogen to give off as much as 1.7 times more energy than it had taken in, a result that appears today in Nature. In subsequent experiments last month, the team was able to produce as much as 2.6 times more energy than was put into the hydrogen fuel.
A photo of the National Ignition Facility is here.  I don't ever see this as commercial energy technology, but hey, if I'm going to be wrong about something, this would be a pretty good candidate for it.

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