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Ball of Light

Photo Essay

1 min read

Photograph: Joe McNally

This giant 10-meter-diameter aluminum sphere serves as the target chamber for the world's most energetic laser system, the National Ignition Facility (NIF) at Lawrence Livermore National Laboratory in California. When completed in 2008, at a cost of US $3.4 billion, NIF will be able to pump out about 2 million joules of ultraviolet energy at a shot, hitting a peak power of 500 trillion watts, though only for a few nanoseconds. Here, a worker measures an aperture through which a 10-20-kilojoule beam of laser light will eventually pass.

The target chamber is the endpoint where NIF's 192 laser beams converge. Each beam derives from a single nanojoule light pulse that is shaped, smoothed, filtered, and amplified a quadrillion times along its 300-meter path to the chamber. Last June, several weeks after the first four beam lines became operational, tests yielded a world record of 10.4 kJ of ultraviolet light in a single beam line.

One aim of NIF is to demonstrate self-sustaining fusion, using the laser beams to create a mass of X-rays to implode and ignite a BB-sized pellet of hydrogen fuel--hence the "ignition" in the name. It's also intended for basic research in astrophysics, materials science, and nuclear physics, and for simulating certain aspects of nuclear weapons explosions.

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