• Number 362  |
• May 7, 2012

NIF fires historic laser shot

The National Ignition Facility, the world's most energetic laser, surpassed a critical milestone in its efforts to meet one of modern science's greatest challenges: achieving fusion ignition and energy gain in a laboratory setting at DOE's Lawrence Livermore National Laboratory. NIF's 192 lasers fired in perfect unison, delivering a record 1.875 million joules (MJ) of ultraviolet laser light to the facility's target chamber center.

This historic laser shot, made March 15, involved a shaped pulse of energy 23 billionths of a second long that generated 411 trillion watts (TW) of peak power (1,000 times more than the United States uses at any instant in time).

"This event marks a key milestone in the National Ignition Campaign's drive toward fusion ignition," said NIF Director Edward Moses. "While there have been many demonstrations of similar equivalent energy performance on individual beams or quads during the completion of the NIF project, this is the first time the full complement of 192 beams has operated at this energy. This is very exciting, like breaking the sound barrier."

The ultraviolet energy produced by NIF (after conversion from the original infrared laser pulse to the final ultraviolet light) was 2.03 MJ before passing through diagnostic instruments and other optics on the way to the target chamber. As a result, NIF, located at Lawrence Livermore National Laboratory, is now the world's first 2 MJ ultraviolet laser, generating nearly 100 times more energy than any other laser in operation.

Satisfying the NIF objective coincides with the third anniversary of the startup of NIF operations in March 2009, when 1 MJ operation was first achieved. Since then, NIF has increased its operational energy about 1 kilojoule each day for three years, a remarkable achievement. Today, NIF is fully operational around the clock, completing important steps toward the goal of ignition and providing experimental access to national and international user communities.

The 1.875 MJ shot exceeds NIF's original design specification and sets the stage for full-power experiments over the coming months. Not only did the shot achieve the highest recorded energy threshold, it also was one of the most precise ever fired at NIF: The energy produced was within 1.3 percent of its goal. Such precision is vital because the energy distribution among the beams determines how symmetrical an implosion is obtained in capsules containing fusion fuel. Implosion symmetry is a critical factor in achieving the pressures and temperatures required for ignition. Moses said that NIF will pursue operations at even higher power and higher energy levels to achieve ignition.

[Don Johnston, 925.423.4902,
johnston19@llnl.gov]