A New Laser For War and Peace

You've seen it all before: intense beams of energy lancing out from attacking spacecraft, piercing tough, armored plating. There's an explosion or two, maybe three. Soon, even the generators that produce protective force fields will fail. The defending vessel will detonate in a thunderous blossom of metals and fuel.

But science fiction isn't real-world combat. On Earth, military lasers have their problems, in particular because of the atmosphere's tendency to absorb and diffuse focused light energy.

Now there may be a solution. A new breed of laser — known as an FEL, or free-electron laser — could finally overcome several obstacles that currently confound deployment. Chief among an FEL's attributes is tunability -- varying wavelengths of lased light could be selected, even during operation. (Traditional, chemically supplied lasers are set at one specific wavelength.) Like tuning to a radio station, picking the right wavelength would make the difference between a strong or weak pulse of energy directed at an incoming target.

Spurring military interest in FELs and other types of lasers is the worry about rogue nations developing and remotely launching strategic and tactical nuclear missiles. The persistent questions about laser weapons' dependability and costs that have limited investment and their adoption are therefore not only being revisited because of geopolitical necessities, but also being addressed by the quickening pace of technological development.

"There's been a lot of hesitation on the part of the individual services to invest in lasers to bring them to the maturity required for combat," said John Albertine, an independent technical laser expert who once headed high-energy laser research for the U.S. Navy. "It wasn't worth the dollars to spend on a technology that may or may not pan out, especially if the defensive weapons you have are sufficient."

"But missiles are expensive and laser fuel — whether it's chemicals or electricity — is very cheap. Plus, lasers can get energy to the target essentially instantly — at the speed of light. High-energy lasers are a unique, new class of weapon."

Deterring attack

One key difficulty facing laser deployment has been a phenomenon known as thermal blooming. Although powerful at the point of origin, and delivered at more than 186,000 miles (299,330 kilometers) per second, a laser's energy can be absorbed and diffused even in relatively instant passage through the atmosphere. The culprits are water vapor, sea spray, suspended particles like soils and volcanic ash, as well as byproducts produced by the burning of organic and inorganic materials.

Depending on exact conditions, an FEL has the ability to mitigate some or most of thermal blooming's effects, in essence delivering energy effectively and directly. FEL defensive capability has led the U.S. Congress to recently approve a $15 million grant to Thomas Jefferson National Accelerator Facility, or JLab, located in the southeastern Virginia city of Newport News. Lab scientists and engineers have created one of the world's most powerful FELs, and the highest average-power FEL known to exist.

"Jefferson Laboratory has by far the highest-power free-electron laser in the United States. The only other is at Los Alamos, and that's a relatively small effort," said Elihu Zimet, head of the Naval Expeditionary Warfare Science and Technology Department at the Office of Naval Research. "From a scientific and technological standpoint, their work is outstanding. They have some of the best people [available] and have shown remarkable progress."

The congressional stipend will go to upgrade JLab's FEL power more than 10-fold, from a current level of 1.72 kilowatts to perhaps as high as 20 kilowatts. At 20,000 watts, the FEL will have more than enough power to disrupt internal electronics or perhaps even burn through fuel tanks. Even at lower energies, the device would still work to deter attack.

"A 10-kilowatt FEL wouldn't effect a hard kill on a missile that is first detected low on the horizon. Nothing would be physically blown apart," Dylla said. "What you're after is disabling the infrared sensors on an incoming missile to prevent it from sneaking up your airplane tailpipe or blowing up your smokestack on the ground."

The Navy, which is charged with overseeing aspects of the upgrade, is keenly interested in a beefed-up FEL because of its potential to disrupt missile-mounted guidance systems. And, unlike competing systems, primarily chemical lasers, FEL lasers are electrically driven, therefore requiring no resupply of consumables in order to operate. Changeable weather poses less of a problem for the FEL's infrared light which, when tuned properly, can pass more easily, even through a turbulent atmosphere.

In the marketplace

What has attracted industrial interest to JLab's FEL is its private-sector potential. Thus far, FEL proof-of-concept experiments have included investigations of assisted chemical-vapor deposition, a technique used to produce high-quality coatings and thin films for electronics and micro-components, as well as the effects of FEL processing on nylon, polyester and a class of materials known as polyimides.

When FEL light is made to shine on a material like fabric, it abrades the fabric's surface, making it softer or better able to absorb smaller quantities of dye without losing color intensity. Likewise, a carpet's surface could be treated with FEL light to make it stain resistant. The manufacturing industry could thus do away with most environmentally hazardous wet-chemical treatments now used during production.

The FEL has the potential to substantially reduce the cost of photovoltaic panels by boosting their light-gathering capacity. Because the solar power industry has been slow to develop because of relatively high manufacturing costs and inefficient sunlight-to-electricity conversion, any significant improvement in either panel production or energy efficiency could lead to a boom in consumer demand.

A host of other FEL applications are also possible, including treatment of packaging to make it more resistant to microbes and food spoilage. The FEL could be used by companies that forge, coat, treat and clean metals of all kinds and businesses that micro-machine materials and parts, as well as semiconductor manufacturers.

By September 2002, as the upgrade concludes, FEL program manager Fred Dylla said interested parties in both the public and private sectors should have a powerful new tool at their disposal. "It's tunable, high-power; and the power is generated efficiently," he said. "If you're looking at defense and industrial applications, those are key."

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