Scientists Taking Laser on Wild Ride; Physicists Stretch Beam's Capabilities

Now that physicists at the Thomas Jefferson National Accelerator Facility have one of the world's most-powerful infrared lasers, what are they doing to do next?

Disneyland isn't on their agenda, despite one researcher's NFL-like TD leap last month when the laser shattered yet another record.

Instead, the Free Electron Laser will spend the summer sending millions of electrons on a wild ride through a funhouse tunnel of magnets as the scientist stretch the FEL's capabilities.

"We'll continue tweaking and practicing lasing over the next two months," said Fred Dylla, the director of the FEL project.

The $34.2 million FEL uses the electron to produce one of the most powerful and controllable infrared light sources ever. When it went online and hit 155 watts June 17, the laser beam was 150,000 times more powerful than those used in supermarket scanners or CD players.

One hundred fifty-five watts may not sound like much. After all, people have 150-watt light bulbs in their homes, Dylla pointed out. That light, however, covers a broad band of light, while the FEL concentrates all its wattage into a powerful beam as wide as an inch to as small as one-eighth the width of human hair.

"Every bit of that power is concentrated into a single wavelength, one color," Dylla said.

The FEL's light show begins when 40 million bunches of electrons a second are spewed into a superchilled 60-foot-long column that revs up the particles to 40 million volts. The electrons are shot out of the column at nearly the speed of light into a series of magnets, called the wiggler.

The magnets cause the electrons to lose some of their energy, which is released as extremely intense light. The beam can then be tweaked by mirrors along its path to change its size, or by the magnets, which alter the wavelength.

News of the Jefferson Lab's success quickly reached similar labs around the world. Congratulations to the 15-member FEL team came via e-mail from Vanderbilt University, which held the previous mark for that kind of laser, and Duke University, whose FEL uses ultraviolet light.

"It's quite an achievement," said the interim director of Duke's FEL, Robert Guenther.

The significance of the FEL is the beam's specific, tunable nature, he said.

"You can't build one of everything." Guenther said. "It's cheaper to build a FEL than a jillion fixed sources" of light.

Word of the FEL's "first light" was also welcomed by the lab's commercial partners. In a few years, when the FEL increases its wattage, industrial giants such as DuPont and Northrop Grumman plan to use it to explore more precise methods of cutting and altering the surface of materials.

The companies, along with Virginia Power, 3M, Lucent Technologies, Xerox and IBM, are members of the Laser Processing Consortium.

Among the possibilities they're interested in are makind durable polymer fabrics for clothing and carpeting; cheap, easily recyclable beverage and food packaging; corrosion-resistant metals with increased toughness; mechanical and optical components with precisely machined features; microcicuitry; and electronics that can withstand extreme conditions.

Next month, three groups of scientists from the LPC will gather at the Jefferson Lab's Newport News facility to run their own experiments.

Virginia Power wants to see how the FEL's light changes the structure of certain metals used in manufacturing turbine blades, said Greg Kessel of the utility's Fossil and Hydro Technical Services group.

The blades are subjected to uneven pressure, which weaken them and shorten their lifespan, Kessel said. Virginia Power wants its turbines to last longer and thinks the FEL could help.

"We need to know all the state-of-the-art processes out there," he said.

Kessel will run experiments in which the Fel's pulsating beam wil hit pieces of metal at a certain wavelength. The laser's high temperature will melt the metal's surface only momentarily, so that the heat is followed by a chilling effect.

This process should change the metal's structure, making it stronger and more resistant to corrosion.

"This is a revolutionary technique. If it works, the sky's the limit," Kessel said, adding the numerous industries, such as shipbuilding, would be interested. "Of course, it's just research now. We haven't proven anything."

DuPont is also interested in how the FEL could change surfaces, expecially polymers.

"The FEL deserves a look-see," said Michael Kelley, a senior research associate at DuPont's Central Research station in Wilmington, Del. Kelley said he hopes to use the FEL to build on research he's done with other types of lasers.

"The FEL is the only kind of laser that can reach the necessary wavelength. It's the only show in town," he said.

Northrop Grumman is thinking of changing that. There are about 19 FELs around the world, most of which are used for research phase. The aerospace company is interested not only in the FEL's ability to micromachine materials, but in the FEL, said Alan To dd, manager of accelerator systems and analysis.

Northrop Grumman is considering entering the FEL world as a supplier of the high-tech laser.

"Our interest is also in the machinery itself. You're looking at a research and development tool here," he said.

For downloadable photos and additional text, please consult http://www.jlab.org/FEL/FELpics/FirstLight/FirstLight.html.