Later this month in California, construction will be completed at Lawrence Livermore National Laboratory’s National Ignition Facility, or NIF, the world’s most powerful laser system—12 years and roughly US $3.5 billion after it was begun. The plan is for NIF’s 192 neodymium lasers to create controlled moments of fusion by focusing their energy on 3-millimeter-wide pellets of deuterium and tritium. Together, the lasers will produce a 500â¿¿terawatt bolt of energy that will turn the surface of a target capsule to plasma. The plasma will then explode, compressing the hydrogen and creating shock waves that will squeeze the fusion fuel even further. The expected result is ignition, the start of a nuclear fire that will burn through the pellets, ultimately releasing up to 20 times as much energy as that introduced by the lasers.
When the project first got off the drawing board in 1996, the U.S. Department of Energy (DOE) had high hopes that NIF would strike three licks with the same stick. NIF’s lasers, any one of which would alone be the world’s most powerful, would help the DOE’s National Nuclear Security Administration to safely maintain the United States’ cache of nuclear weapons. Without any test detonation, NIF would validate supercomputer-generated three-dimensional simulations of a thermonuclear burn. The project’s champions also insisted that the 30â¿¿meter-tall behemoth would help scientists to better understand how to turn water into limitless amounts of carbon-free energy. And the project would advance basic astrophysics research, for example by simulating the explosion mechanisms inside supernovas.
The project, which broke ground in 1997, was supposed to be completed in 2002, at a cost of $1.07 billion. But technical problems triggered an avalanche of construction delays and cost overruns. So in 1999, the DOE swept the decks of NIF’s management. The facility finally came in at about $3.5 billion and has met all its construction and spending targets since 2001, when its budget was adjusted to reflect what it would actually cost to complete.
By last December small-scale experiments had already begun, with researchers working two shifts a day, seven days a week, says Edward Moses, principal associate director in charge of NIF.
”We just did an experiment with the lasers running at 500 kilojoules,” Moses says, though he won’t discuss the specific aims of the work scientists were doing prior to the facility’s official opening. ”That’s 20 times more than has ever been done before.” Moses is confident that NIF will reach ignition when experiments aimed at achieving it begin in 2010. By 2012, he expects the Lawrence Livermore team to be able to start fusion reactions on demand and get 20 times as much energy as they put in.
But some scientists both inside and outside the DOE grumble that NIF will make only a marginal contribution to the understanding of how best to maintain the United States’ existing nuclear weapons stockpile [see ”What About the Nukes?” in this issue]. ”There is some science you can learn from NIF, but after you’re done and you’ve spent upwards of $4 billion, the question you have to ask is whether it’s worthwhile,” says Ivan Oelrich, vice president for strategic security at the Federation of American Scientists, which issued a report in 2007 critical of NIF and two other big National Nuclear Security Administration’s Stockpile Stewardship Program projects. The report asserts that NIF’s funding would have been better spent on smaller, targeted research projects at the national laboratories or at dozens of universities.