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See Inside June 2009

Data Points: A Flash of Fusion

On May 29 Lawrence Livermore National Laboratory dedicated the National Ignition Facility, the world's biggest laser system. It will direct laser beams from all directions onto a pencil-eraser-size pellet of frozen hydrogen (housed in a tube called a hohlraum), heating it to millions of degrees and inducing fusion. The laser beams must travel some distance to pick up energy from amplifiers and hit its tiny target; the lab likens the accuracy to a pitcher at AT&T Park in San Francisco throwing a strike at Dodger Stadium in Los Angeles. Designed to ensure that U.S. nuclear warheads work properly in lieu of actual testing, the facility will also provide a means to study the interior of stars and fusion as an energy source.

Number of laser beams that hit the target: 192

Number of “control points” to amplify and maintain the beams: 60,000

Laser travel distance: 1 kilometer

Time in which all beams must strike target, in trillionths of a second: 30

Energy delivered to target, in joules: 1.8 million

Initial cost estimate: $1.1 billion

Actual final cost: $3.5 billion

Initial construction time estimate: 6 years

Actual construction time: 12 years

This article was originally published with the title "A Flash of Fusion."

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