BUILDING & PROMOTING THE FEL

Lasers are in more demand than ever. Technological advances have allowed lasers to perform functions that were never before possible. They have also allowed for the creation of new kinds of lasers.

One such laser is the Free Electron Laser (FEL). Although the idea of an FEL has been around for some time, Jefferson Lab has enhanced the concept into an efficient product. The FEL works a lot like a regular laser except it is capable of eliminating energy problems.

Fifty thousand watts of electricity are required to power the initial beam. Once the beam is sent back through the cavity, only 5,000 watts are required to power the next beam. The rest of the power comes from the beam that has already been accelerated. Recycling the electron beam makes the FEL extremely energy efficient.

"A big portion of the FEL task is recirculation," said George Biallas, systems manager for the beam transport system. "We are very dependent on the recirculation to create enough energy for the machine to run. Without recirculation you only get 100 watts of power as opposed to the 1000 watts you get with recirculation."

Developing the Laser

Fred Dylla, FEL Program Manager, says sufficient funding to start the first phase of the FEL project came through in June of 1996. The funding will last through fiscal year 1997, and will pay for the building of the infrared FEL and the Free Electron Laser Facility (now under construction). The funding is coming from a variety of sources, including the U.S. Navy, the Department of Energy, the Commonwealth of Virginia, and two industrial partners who will help build the laser and some of the equipment for user labs. "Close to $20 million will be spent by the end of fiscal year 1997," says Dylla. Money for the project was also appropriated in this year's U.S. Defense Bill, and potential support is being lined up by the Department of Defense and DOE for fiscal years 1998 and 1999.

In order to make the FEL cost effective, some major boundaries must be crossed. To use the laser for surface processing it must output more than 10 kilowatts of power. "That's because these manufacturers produce a lot of stuff. Dupont makes 20 billion pounds of nylon per year. It takes a lot of light to process that so you've got to make a big laser," says Neil. He adds that if the laser is used for micro-machining, one kilowatt may be enough to satisfy some of the applications for which the FEL would be used, but the laser must still be cost effective.

Another boundary that must be overcome involves the laser's injector. Robert Legg coordinates the commissioning plans for the FEL, and is currently working on the injector. Legg says the problem deals with the ceramics that hold off the high voltage on the electron gun, which is a component of the injector. When the electron gun operates, small electron currents are emitted. Without much voltage, an intense electric field pulls electrons off the body of the gun and embeds them into the ceramics. The problem is the ceramics can't handle the high voltages needed in order for the gun to operate properly (about 350,000 volts). "The ceramics are dielectric, they can't dissipate the electrons that hit it," said Legg. " So if you go to very high voltages it just breaks down." Several new ceramics are being manufactured to solve the voltage problem. A tube with a special coating is also being manufactured. This tube will suppress the electron currents that are emitted from the gun. Both items should be ready sometime this month," says Legg.

Applications

"If this material could be made with its present durability but more comfortable, you'd have a real product," he adds. Dupont has already made a small quantity of the enhanced nylon and it is of good quality. The problem, says Neil, is that it took Dupont one hour to make one square meter because their lasers are not powerful enough. The FEL would enable them to make thousands of square yards per day. "That's enough to go into trial manufacturing and show that there is a market for a cloth like this, and what the economics of making clothes like this would be," says Neil.

In metals, a strong absorption of the pulses can melt a shallow surface layer. This will result in a smooth glassy finish that is resistant to corrosion. "Corrosion naturally attacks metal at grain boundaries," explains Neil. "If you can eliminate those grain boundaries, you get a resistance factor of 10 to 100 to resist attack by corrosives."

The laser can also alloy the surface of materials. Using this process, the laser can alloy just the surface layer, allowing all the benefits of the metal to be obtained on the outer surface. This process is considerably cheaper than conventional methods because only a small amount of the material is used.

A metal that is highly resistant to corrosives could be used for turbine blades at nuclear and steam plants. Neil states that turbine blades need replacing every five years. In order to replace the blades the entire plant must be shut down for a week to 10 days, all of which is time lost for the plant. The metal treated by the laser would have doubled the lifetime of the metal used for the current blades. "The plant is worth a lot of money to keep on line. Industry would be willing to spend a lot of money to double the life of the turbine blade," explains Neil. "Imagine if we could improve it by a factor of five or more? This is big money. The estimate is that processing alone could be worth about one billion dollars a year."

Neil explains that if the light emitted from the laser is ultra violet light, as opposed to an infrared light, it is possible to change the chemical make up of a material. With polymers, it breaks the chemical bonds and an amine group pops above the surface. This amine group has the ability to kill bacteria. "It's still bound to the plastic, it doesn't wash away," Neil says. "What it means is hospital gowns could be made that wouldn't carry germs around from one room to another. Doctors could wear them into surgery and wouldn't have to worry about carrying infections around on their rounds." Neil adds that the plastic could also be used to make a wrap for foods in grocery stores that would kill bacteria and prevent the foods from spoiling. "We need to get the UV system before we can test this because this is a chemical interaction. It has tremendous commercial prospects and Dupont is very excited about it. They could sell a lot of this if we can make it for a reasonable price," says Neil.

In addition to all of the above mentioned applications, it is believed that there are even more applications that have yet to be thought of.

"In fiscal year 1998 we will have to make the laser work. That will be a six month effort," says Court Bohn, Deputy Program Manager for the FEL. "In the middle of 1998 we will start to use the laser for the first experiments." A large group of scientists, engineers and technicians are presently putting in long hours to make this program a success, and according to Bohn, all things are going well and prospects for additional funding "look good."

"It's a great technical challenge and we're getting terrific support, dedication, and creativity from not only the core team, but the whole Accelerator Division," says Neil. "We hope to spin-off the technology and develop commercialized versions of this and, along with some of our partners, produce something that can be manufactured in industry and located on the industry's sites. Then they can take over the processing and incorporate the light output into the rest of their manufacturing as the material comes off their manufacturing line."

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Updated January 20, 2004