From a distance, the concrete bulk rising out of the arid landscape surrounding Livermore, Calif., could be mistaken for an indoor sports stadium. The huge building being erected at the Lawrence Livermore National Laboratory for the National Ignition Facility (NIF) is two football fields long. Its glassed-in atrium is cluttered with posters and plaques, and upper observation tiers let spectators gaze into the interior through panoramic windows.
But instead of teeming with activity, the cavernous NIF is nearly deserted, silently awaiting either distinction or obsolescence.
When the U.S. Department of Energy first conceived of the NIF in 1994, the project sounded like something out of an Isaac Asimov novel. Its crowning glory, planners said, would be a high-powered array of 192 lasers, each capable of emitting a beam wider than a dinner plate. Mirrors would reflect all 192 beams into a 9-meter-wide aluminum target chamber, where they would converge at a single, infinitesimal point, smashing hydrogen atoms together in a nuclear fusion reaction like those that fuel the sun.
If that reaction ever takes place, NIF scientists claim, it would represent a critical breakthrough in nuclear weapons testing. A facility that could produce fusion in controlled conditions could allow weapons specialists to simulate the detonation of different types of bombs, helping them assess the status of aging atomic stockpiles without conducting the risky test explosions that international law is trying to ban.
More than a decade after the NIF's inception, however, its future is in limbo. Many scientists and lawmakers question whether the facility can achieve its stated scientific goals--and whether such a money-draining marquee project was really necessary in the first place.
In the project's defense, NIF officials point out that they achieved several important milestones last year, including installation of more than 1000 of the facility's 6000 optical and instrumentation units--precision electrical and optical devices that guide the laser beams into the target chamber [see photo, " "]. Eight of the 192 planned beams are up and running, and a series of experiments last August verified that the eight-beam "bundle" can produce 153 kilojoules of targeted infrared laser light, making it the most powerful laser array in the world.
Nevertheless, detractors in high places have kept up a steady barrage. Last summer, a congressional committee led by Sen. Pete Domenici (R-N.M.) proposed axing the facility's funding altogether on the grounds that it has sucked money from the federal government's coffers every year with no definite indication that its scientific goals will ever be fully met. NIF officials currently figure the facility will achieve fusion ignition in 2010, eight years behind the origi-nal schedule, and the project's cost is now projected to exceed US $4 billion, up from the initial estimate of $2.1 billion.
NIF advocates chalked up a much-needed victory in November. A Senate joint committee ignored Domenici's recommendations, granting all but $10 million of the Bush administration's $337 million 2006 budget request for the project. Hearing the facility's funding had come through "was like a revalidation," says Bruce Warner, the NIF's deputy associate director. "This tells us that the government believes we've managed the project well and they like what they see."
Despite the triumph, questions remain about the project's ability to live up to its larger-than-life billing. "Although we've settled on continuing construction at NIF, I remain skeptical that [the Department of Energy] will be able to deliver on its promises regarding schedule, cost, and scientific capability," Domenici said in a statement released after the budget vote. Now that the facility's physical construction is almost complete, the 2007 budget request for the NIF is $29 million less than the year before, but even so, Congress's attitude is uncertain.
Doubters such as Domenici see the NIF, despite the formidable home being built for it, as a ramshackle, multibillion-dollar house of cards. And they have some support from qualified experts. A panel of the Jason group--leading scientists with top security clearances who regularly give the government advice about cutting-edge military technologies--recently released a report detailing technical difficulties that could stymie the NIF's goals and questioning the validity of some of the scientific principles underlying the facility's planned fusion experiments.
Foremost among the Jason panel's concerns is the question of whether a fusion reaction that occurs inside a capsule smaller than a fingernail can provide an accurate indication of how a full-size nuclear weapon would detonate. "It's a mistake to assume that NIF experiments are going to be directly relevant to weapons testing," says panelist Richard Garwin, a semiretired IBM physicist who has served on the president's science advisory committee. "The temperatures in the NIF chamber are much lower than they are in actual nuclear weapons, and the amounts of material being tested are much smaller."
NIF physicists apply computer-generated formulas to their experimental data in order to account for such scale differences. But Garwin says that instead of relying on unproven formulas to indirectly assess the status of existing weapons stockpiles, the government would be better off simply replacing the fusion-dependent components of weapons on a regular basis.
Raymond Jeanloz, a physicist at the University of California, Berkeley, who plans to use the finished facility for experiments that replicate fusion conditions inside stars, agrees that the correlations between NIF experiments and real-world explosions aren't yet proven. "That's one of the areas people will want to investigate as the facility gets up and running," Jeanloz says. He points out, though, that change-of-scale calculations are nothing new for most physicists--earthquake motion is regularly simulated with large syrup tanks, for instance.
"When we first started trying to replicate the conditions inside stars on a 100-micrometer scale, people said it couldn't be done," scientific group leader Bruce Remington says. "A decade later, hundreds of laboratory astrophysics papers have been published in peer-reviewed journals, and about 50 percent of them address scaling issues."
The NIF's scaled calculations will be accurate, Remington contends, because staff physicists have an intimate knowledge of how the physical properties of matter can change depending on how much of it is present. For instance, small amounts of the ionized gases generated in fusion reactions produce proportionally more heat-creating friction than larger amounts, and weapons simulation formulas are tailored to account for that factor.
The Jason panel is also concerned about whether the NIF's lasers will be able to ignite fusion at all. Because of laser backscattering--incoming laser beams are distorted by the superheated clouds of plasma forming around them--light leaks out of the capsule that encloses the target molecules, lessening the intensity of the beams. NIF scientists claim, however, that the concern is overblown and that the lasers' focusing capabilities will minimize excess plasma formation.
Another potential issue is whether the facility's precision-ground focusing lenses will be able to stand up to the heat. In previous tests under conditions similar to those the NIF researchers hope to create, optical equipment has simply shattered. "There's a question as to whether the glass can withstand such a high degree of power," says Robert Civiak, a retired physicist who compiled an independent report on the NIF for the White House's Office of Management and Budget.
Although Remington acknowledges that Civiak's concern has some merit, he says the solution is for facility administrators to be selective about allowing researchers to operate the laser at full strength.
Novelist E.L. Doctorow has likened the process of discovery and new thought to driving at night, on an unfamiliar highway, with headlights that barely illuminate the road ahead. Because NIF scientists cannot foresee small or large problems that may arise as they move toward the goal of achieving fusion--or, for that matter, all the exciting science that could come from NIF experiments--the ultimate value of the project cannot be fully assessed in advance. But of course the government agencies bankrolling the NIF would prefer the entire highway to be brightly lit.
"We're going to go through some difficult learning exercises," Remington says. "The facility's hardware is working well, but we have to make all of the beams work together, shoot at the same time, and point at the same place. There'll be a lot of hand-wringing figuring that out."
Meanwhile, for other NIF employees, work continues as usual, though they remain cognizant that factors beyond their control--whether fiscal or physical--could cut short their years-long quest. "We have high confidence that we're building the right thing," NIF physicist John D. Lindl says. "But the bottom line is that NIF is still an experiment, and the only way to prove fusion can be done is to demonstrate it with a facility that works."