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Moses Fired Up Over NIF Start

Photonics.com
Jun 2009
In 2012, according to fans of fringe "science," the world as we know it will come to an end - apparently because the Mayans failed to develop the perpetual calendar. By then, however, we just might have solved many of the deepest mysteries of the universe.

NIFMoses.jpg
Dr. Edward I. Moses, principal associate director for the National Ignition Facility (NIF) and Photon Science Directorate at Lawrence Livermore National Laboratory, speaks about NIF during the CLEO plenary session Monday night. (Photonics Media photo by Lynn M. Savage)

On Monday evening at CLEO, Edward I. Moses of Lawrence Livermore National Laboratory described the construction of and aspirations for the National Ignition Facility (NIF). Originating in the form of an official design report issued in 1994, the world's most powerful laser-and-optics system recently broke the 1-MJ mark. Experiments will ramp up over the next 18 months, with the goal of increasing the total power generated by the facility's 192 combinable lasers to the tens of megajoules, eventually having a stable burning platform inside three years that will be made available for high-energy-density researchers from around the world. Ultimately, yields of up to 100 MJ should be possible.

People joke that "fusion is 50 years away, no matter when you ask," Moses said during a plenary speech in front of an audience of about 200 to 300. "But NIF could make it happen in two years."

Fusion in particular, and high-energy-density physics in general, are the foci of the NIF, with the hope that plasma experiments not possible anywhere else will lead to discoveries about star formation and other events that define how the universe works.

According to Moses, nothing about the NIF has been typical or easy. For example, most elements of the building had to be constructed to a tolerance of 200 µm. Because of the key role of optics with high energy tolerance needed to support the score of lasers, 150 tons of neodymium glass had to be produced.

Ignition samples, such as gold hohlraums (tiny coated pellets) or minuscule diamonds, must be held at the focal point of the lasers at near absolute zero to a tolerance of 10 µm. The laser produces beam widths of 150 µm to a few millimeters, and the beams can be pointed to within 60 µm. Deformable mirrors with 39 elements are used on each beam line to produce interferograms 1 s before firings to correct any possible alignment issues on the fly.

When fired upon, samples reach a temperature of 10 million kelvin; the pellets are destroyed in about 20 ns, but before then, they emit x-rays and undergo chemical processes that have only been guessed at until now.

In what Moses sees as being a relatively short time, the NIF could answer such questions as how elements heavier than iron are created? (It has been presumed that heavy elements are born in supernovae, but NIF can be used for repeatable experiments for first time.) The NIF may also provide insight into what chemical processes occur at millions of atmospheres of pressure?

Moses also suggested that the audience keep an eye on the Laser Inertial Fusion-based Energy (LIFE) program, which could use the power of the NIF to produce a lot of energy out of very little matter. Even unwanted material, such as depleted uranium and weapons-grade plutonium, could be used to produce useful energy instead of creating headaches over disposal.

"Over the next few years, you'll see just how big and how important ignition research has become."

Perhaps it would be better if the world survives 2012 after all.

Lynn Savage
Features Editor
lynn.savage@laurin.com


GLOSSARY
fusion
1. The combination of the effects of two or more stimuli in any given sense to form a single sensation. With respect to vision, the perception of continuous illumination formed by the rapid successive presentation of light flashes at a specified rate. 2. The transition of matter from solid to liquid form. 3. With respect to atomic or nuclear fusion, the combination of atomic nuclei, under extreme heat, to form a heavier nucleus.
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