The National Ignition Facility [NIF] in California, US, is the world’s leading nuclear fusion research lab. Fusion is the stuff stars are made of, literally. Heat energy in the billions of degrees, and pressure in the billions of atmospheres, forces hydrogen atoms to fuse, releasing energy and helium, as well as sustaining further reaction.
Recreating these conditions on earth could very well be the holy grail of energy research, or pandora’s box. Researchers hope that nuclear fusion might replace the currently-used nuclear fission reaction. Fusion is expected to be a cleaner source of power than the current uranium-based reactors, but so far, no controlled fusion reaction has hit the ignition point.
The US Congress, which funds NIF, had set a deadline of September 30, 2012, which has come and gone, without a hint of ignition. NIF was trying to recreate the high temperature and pressure at the heart of a star by using a pulsed-implosion technique. By focusing 192 individual lasers on a single point, with less than a hair-breadth tolerance, NIF was attempting to implode tiny balls of frozen hydrogen, hoping that the resulting pressure-increase over billionths of a second would raise the temperature enough to initiate a fusion reaction.
“We’ve reached 150 to 200 gigabars in implosions, but that’s still off by a factor of 2-ish,” said Ed Moses, Lawrence Livermore National Laboratory and principal associate director for NIF. The ignition attempts have been a very complicated affair, the implosion velocity has to be correct, the hydrogen pellet has to form a perfectly spherical hot-spot, plasma has to be properly mixed once formed, and compression has to be even. “We can do all of these things. The trouble is that we can’t do them all at once,” continued Moses. “Like squeezing on a balloon, something might pop out.”
Even though NIF’s nuclear fusion ignition attempts have failed, they still have enough funding to continue testing for another year or so. Even then, they may remain in operation to increase knowledge of how atomic weapons function and break down over time, especially considering the stockpiles of nuclear weapons that still exist scattered all over the world.
[via new scientist]