The firing of the National Ignition Facility, or NIF, at Lawrence Livermore National Laboratory, located 40 or so miles east of San Francisco, wasn’t an earnest attempt at a more-energy-out-than-you-put-in “ignition” of fusion, the same process that merges atoms at the sun’s core — and the facility’s ultimate goal. Yet the staff and independent researchers working with the $3.5 billion machine have reason to be optimistic about achieving fusion within two years, even if much of the device’s time is earmarked for defense research and prospects of near-limitless and pollution-free energy aren’t certain.
“In my mind, to have accomplished this shot is an almost unfathomable scientific achievement,” Paul Drake, a physicist at the University of Michigan using NIF as a proving ground for studying supernova physics in the laboratory, told Wired.com. “I’ve had a lifetime of experience of big science facilities, and find myself in awe of [the NIF team] having made this thing work this fast.”
The research facility’s construction began in 1997 and spreads over an area nearly the size of three pro league football fields, most of the space occupied by equipment that revs up 192 laser beams. During the Sept. 29, 2010 firing of the laser, scientists and engineers funneled these beams into a 30-foot-diameter metal sphere at the end of the complex. At the center of this chamber, a tiny plastic pellet filled with heavier forms of hydrogen received a punishing 1 megajoule zap, similar to the instantaneous oomph of a car traveling 100 mph.
According to engineering physicist Edward Moses, who heads up the NIF team, the laser burst was about 75 percent of its full energy capacity. In addition, the cryogenically cooled pellet was filled with deliberately less-than-perfect fuel.
“The last thing we’d ever think about doing is playing cowboy with this thing,” Moses said. Throughout the next year or two leading up to an all-or-nothing firing, the facility will make similar integrated shots about once a month.
Richard Petrasso, a fusion scientist at MIT who works with the machine’s diagnostic equipment, said the tiptoeing is for a good reason.
“The facility is like a new car engine,” Petrasso said. “You don’t hit the pedal all the way down to the ground the first time. You have to tune it to get all of the conditions just right — the laser, the diagnostics and the surface of the capsule.”
About 10 trillion neutrons zoomed out of the capsule during the test shot, signaling the successful fusion of some tritium and deuterium atoms — the “heavy” hydrogen fuels in the pellet. Moses said 1,000 times more neutrons should fly out during the ultimate goal of a fusion chain reaction.
“We’re still proving we can do experiments we want, and also for the broader scientific community,” Drake said. “But without hesitation, I’d say NIF is on track for doing some pretty awesome science,” including simulating Jupiter’s oddly magnetic core, the innards of stars and other hot-and-dense environments around the universe.
At the end of the day, however, most of NIF’s operating time isn’t slated for doing fundamental science. Moses said about 10 percent of the machine’s time is dedicated to that now and will go up to 20 percent after 2013. Another 40 percent (by 2013) is hedged for more ignition research, and the remaining 40 percent chunk will be for gathering data about fusion physics for the government. In other words, it will simulate fusion bomb explosions without detonating them.
“Strategic security is also part of the mission,” Moses said. “We want to make sure we can build virtual test sites on computers, but we need good data to ground the models.” If NIF achieves fusion burn, he said it will be the only facility of its kind to safely create the conditions of active weapons.
Beyond NIF’s three-pronged mission, there’s also the promise of developing a safe fusion energy source that releases 30-40 times the energy put in. The only theorized “pollution” would be helium, which is the universe’s most pervasive and inert gas.
“The energy potential is there, for sure,” Petrasso said. “The question is about practical implementation. There are a lot of … issues that have to be dealt with to turn it into a reactor that makes energy.”