Navy Tries Again With Laser
Entering a seemingly futuristic world more familiar to fans of Star Wars, Battlestar Galactica and all things Trekkie, the Navy is going laser.
Underneath a nondescript research building off Interstate 64, scientists with the Department of Energy's Thomas Jefferson National Accelerator Facility have built the most powerful, free-electron laser in history.
Using millions of dollars from the Navy, Jefferson Lab researchers expect by the end of the summer to increase the power to 10,000 watts, or 10 times the power of the groundbreaking version tested two years ago.
Within six years, scientists now predict, advancements should increase the laser's strength 100 times to a megawatt, giving the Navy technology powerful enough to shoot down enemy missiles.
Navy officials in charge of the project said progress has exceeded their expectations.
"The primary threat to surface ships is the cruise missile that will be faster and more maneuverable," said Michael B. Deitchman, acting head of Expeditionary Warfare Department in the Office of Naval Research in Arlington.
"With a high-powered, free-electron laser weapon, you could quickly aim and intercept the threat. It will take a few seconds of time, but you could still blind the missile or physically destroy it before it reached the ship."
Scientists said the Navy will benefit even if it doesn't install laser weapons on ships in the near future.
"We're getting funded by the Navy to make this high-power laser so that the Navy can use it to protect their ships," said George Neil, the laser project's deputy program manager. "Or, at the very least, if it can't be used for that, they want to know what the limits are in case somebody else wants to try to build one, they know what they might have to defend against."
The free-electron laser, overseen by a team of 25 at Jefferson Lab, is about 160 feet long and 25 feet wide. A smaller, conventional laser feeds it electrons.
Unlike a solid state laser — think of a laser pointer — or a chemical laser, the free-electron technology doesn't require electrons to be at any fixed energy level within atoms. A particle accelerator controls the energy levels, making the laser uniquely "tunable" to different wavelengths.
Electrons are then shot into a magnetic field called a "wiggler," which causes the electrons to emit light. The process essentially transforms the energy electron beam into infrared light.
That light, in rapid-fire bursts less than a billionth of a second long, produces the free-electron laser beam.
But don't expect a stream of bright, yellowish light like Star Trek phasers used by Capt. Kirk. The free-electron laser will be invisible as it shoots through the air, though it's likely to glow brightly when it strikes its target.
The Navy has been down this road before. In the 1980s, $1 billion was spent on laser research that culminated in a functioning 1-megawatt chemical laser. But that laser would distort if used in wet environments, preventing the weapon from focusing on a target.
"The Navy's program came under great criticism from admirals who said, 'Great. You've given me a shipboard laser that will work great — if I'm ever attacked in the desert,'?" Neil said.
That technology, requiring the use of hazardous chemicals on a ship in potentially rough seas, was ruled out as unsafe, too.
Jefferson Lab scientists said the free-electron laser has two central advantages.
The first is its wavelength tunability, a feature that would allow the Navy to set the laser to work in a humid, salty environment. The chemical laser is restricted to a single wavelength that cannot be used effectively at sea.
The second advantage lies in its power.
"One of the admirals that's directing some of the programs calls the laser 'dazzle,' for dynamite at the speed of light," Neil said.
A future fleet of electric-power ships will be able to accommodate and energize a free-electron laser without outside refueling.
"We fill up the tank, if you will," Neil said. "And you never need to fill it up again."
Though the laser only uses about 1 percent of the energy produced by the accelerator, scientists said that over 90 percent of the leftover energy is recycled rather than wasted by rerouting it back into the system.
Jefferson Lab, operating as a nuclear physics research complex since 1994, is built around the world's first large-scale superconducting electron accelerator, which serves some 1,600 scientists around the world. The free-electron project started in 1996.
Since then, the Navy has contributed about $30 million to the effort. The Air Force, the Commonwealth of Virginia and several private companies have also supported the project. But it is the Navy that appears to be heading for a long-term commitment of six more years at $10 million a year, according to bills pending in Congress.
H. Frederick Dylla, the project's manager, said researchers already have seen the benefits of a powerful, free-electron laser, including the more efficient production of a superstrong molecule of carbon known as a nanotube, and experiments into mysterious light known as the terahertz that could be used potentially for anthrax detection.
As the laser comes up on another milestone, scientists said their massive laboratory device must be made more robust, more compact and more user-friendly if the Navy hopes to make it operational by sailors rather than PhD's.
"We're still in the learning stage to see whether it makes sense or not," Neil said. "But we won't be able to tell the Navy whether it's practical. That's a decision they'll have to make."