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The Navy is increasingly excited about building a superpowerful laser to shoot down missiles and rockets that might attack its ships. But don't expect the long-planned Free Electron Laser weapon to replace the guns the Navy stations on its ships – or to be shipboard for years. And definitely expect the laser to do more than just zap stuff out of the sky.

Sure, everyone wants a "death ray," as the Navy's chief of research, Rear Admiral Nevin Carr, put it yesterday. But the program manager at the Office of Naval Research for the Free Electron Laser, Quentin Saulter, tells Danger Room that the Navy is looking at "multiple uses, not a single use" for its "Holy Grail" of lasers. And that might lighten the laser's energy burden.

What would the laser do when it's not trying to blast a missile out of the sky? "It can be used as a sensor," Saulter says in an interview during the Office of Naval Research's science and technology conference in Virginia. "It can be used as a tracker... It can enable kinetic kill systems to be more precise. It can be used for location, time-of-flight location, information exchange, can be used for communications, it can be used for target designation, it can be used for disruption."

Of course, spending hundreds of millions on another laser tracker might raise eyebrows. But this laser isn't like others. All lasers work by using energy to charge atoms into generating and then focusing light, requiring a medium – some use crystals, others use chemicals – to filter that light into powerful beams along a particular wavelength. But the Free Electron Laser uses supercharged electron streams to operate along multiple wavelengths, making it more powerful.

Little wonder the Navy's embarked on an open-ended, $163 million project to develop one into a weapon. Last September, it gave Boeing $26 million task order to develop a prototype design for the laser – the company completed a preliminary design in March – that'll deliver by early 2012. If it works, the Navy will be on its way to a speed-of-light weapon aboard its ships that won't have to reload, since it'll rely on a ship's energy source for powering up. Not a bad thing if you're worried about a cruise missile slamming into your hull.

But that's still a big if. Boeing's design has to generate the 100 kilowatts of energy generally considered to be military grade. The Free Electron Laser at the Department of Energy's Jefferson Lab in Virginia generates only 14 kilowatts. Particles in the air like condensation can reduce the potency of even a free-electron laser – and there's a lot of condensation in sea air. And 100 kilowatts is pretty much the entry level to weaponize a free-electron laser. It's going to need a lot more power to take down powerful projectiles like the huge "carrier killer anti-ship ballistic missile the Chinese are developing. And how much power will it require from ships, especially now that the Navy leadership is trying to get half its energy from alternative fuels by 2020?

Saulter isn't sweating it. "All lasers are inefficient users of energy," he says. Right now, the model at use at Jefferson uses an oscillator, with energy stored up in its cavity, and runs at 10 percent efficiency. He's "99.99 percent confident" the Free Electron Laser can get to 100 kilowatts: Boeing will have to improve efficiency or pump ten times more power into it. The same applies to scale up its energy output.

That should be an easy energy burden to shoulder, Saulter figures. "One Naval generator, on all the ships they're planning on building in their more-electric fleet capacity, can put up to two megawatts of power," he continues. "Of course, the Navy plans on having more than one generator on its vessels... 100 kilowatts is not a power constraint for a naval weapons system for an FEL. It is something that is doable today for a hundred-kilowatt system."

But use the laser for something other than burning a missile out of the sky, and the required energy dose drops. "Being that there are multiple different types of ways to protect" a ship – using the laser as a targeting system for on-board guns or a sensor, for instance – "means that not all things require 100 kilowatts. Maybe some of those waves only require 1 kilowatt. Maybe some of those waves only require only 50 watts."

Development is to take place at Boeing's directed-energy labs in Albuquerque, with additional research taking place at the national laboratories at Argonne, Los Alamos and Brookhaven; the Naval Postgraduate School; Yale and other locations. It'll be years before shipboard tests can even take place, let alone getting it out into the fleet.

But for now, the Office of Naval Research wants you to stop thinking of the laser as just a zapper. "If you were to develop a car, you would want your car to go from zero to 100," Saulter says. "You wouldn't want to turn your car on and immediately go to 100... The way that we think of defense and protecting our people is to have layers of capability to ensure the protection of our people before we ask them to go into harm's way." He pauses, grinning. "We still want the car to go to 100, though."

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