NEWPORT NEWS, Virginia — Walking into a control station at Jefferson Labs, Quentin Saulter started horsing around with his colleague, Carlos Hernandez. Saulter had spent the morning showing two reporters his baby: the laboratory version of the Navy’s death ray of the future, known as the free-electron laser, or FEL. He asked Hernandez, the head of injector- and electron-gun systems for the project, to power a mock-up electron gun — the pressure-pumping heart of this energy weapon — to 500 kilovolts. No one has ever cranked the gun that high before.
Smiling through his glasses and goatee, Hernandez motioned for Saulter to click and drag a line on his computer terminal up to the 500-kV mark. He had actually been running the electron injector at that kilovoltage for the past eight hours. It’s a goal that eluded him for six years.
Saulter, the program manager for the free-electron laser, was momentarily stunned. Then he realized what just happened. “This is very significant,” he says, still a bit shocked. Now, the Navy “can speed up the transition of FEL-weapons-system technology” from a Virginia lab to the high seas.
Translated from the Nerd: Thanks to Hernandez, the Navy will now have a more powerful death rayaboard a future ship sooner than expected, in order to burn incoming missiles out of the sky or zap through an enemy vessel’s hull.
“Five hundred [kilovolts] has been the project goal for a long time,” says George Neil, the FEL associate director at Jefferson Labs, whose Rav 4 license plate reads LASRMAN. “The injector area is one of the critical areas” of the whole project.
The free-electron laser is one of the Navy’s highest-priority weapons programs, and it’s not hard to see why. “We’re fast approaching the limits of our ability to hit maneuvering pieces of metal in the sky with other maneuvering pieces of metal,” says Rear Adm. Nevin Carr, the Navy’s chief of research. The next level: “fighting at the speed of light and hypersonics” — that is, the free-electron laser and the Navy’s Mach-8 electromagnetic rail gun.
Say goodbye to an adversary’s antiship missiles, and prepare to fire bullets from 200 miles away, far from shoreline defenses. No wonder the Navy asked Congress to double its budget for directed-energy weapons this week to $60 million, most of which will go to the free-electron laser.
It won’t be until the 2020s, Carr estimates, that a free-electron laser will be mounted on a ship. (Same goes for the rail gun.) Right now, the free-electron laser produces a 14-kilowatt beam. It needs to get to 100 kilowatts to be viable to defend a ship, the Navy thinks. But what happened at Jefferson Labs Friday shrinks the time necessary to get to 100 kilowatts and expands the lethality of the laser. Here’s why.
All lasers start off as atoms that get agitated into becoming photons, light that’s focused through some kind of medium, like chemicals or crystals, into a beam operating on a particular wavelength. But the free-electron laser is unique: It doesn’t use a medium, just supercharged electrons run through a racetrack of superconductors and magnets — an accelerator, to be technical — until it produces a beam that can operate on multiple wavelengths.
That means the beam from the free-electron laser won’t lose potency as it runs through all the crud in ocean air, because its operators will be able to adjust its wavelengths to compensate. And if you want to make it more powerful, all you need to do is add electrons.
But to add electrons, you need to inject pressure into your power source, so the electrons shake out and run through the racetrack. That’s done through a gun called an injector. In the basement of a building in Jefferson Labs, a 240-foot racetrack uses a 300-kilovolt injector to pressurize the electrons out of 200 kilowatts of power and send them shooting through the accelerator.
Currently, the free-electron laser project produces the most-powerful beam in the world, able to cut through 20 feet of steel per second. If it gets up to its ultimate goal, of generating a megawatt’s worth of laser power, it’ll be able to burn through 2,000 feet of steel per second. Just add electrons.
And that’s why Hernandez’s achievement is so important. He shrugs, concealing his pride. A powerful accelerator at Cornell University is “stuck at 250″ kilovolts, he grins. And he’s on a roll. Hernandez’s team fired up the injector in December with enough pressure to prove the FEL will ultimately reach megawatt class. Steel: Beware.
“It definitely shortens our time frame for getting to 100 kilowatts,” Saulter says, and it produces a “more powerful light beam.” But he won’t speculate on how much sooner this means the laser can get into the fleet. In any case, the Navy doesn’t yet have the systems to divert the amount of power from its ships’ generators necessary to operate the laser, but anticipates it will by the 2020s.
There are still a lot of obstacles to getting the free-electron laser onto a ship. The 240-foot racetrack that Neil built at Jefferson Labs — a scale model of one that’s underground here, seven-eighths-of-a-mile long — is way too big. Boeing has a contract to build an initial workable prototype by 2012, but by 2015 the racetrack has to be much, much smaller: 50 feet by 20 feet by 10 feet. And as the model shrinks, it’s got to get more efficient in harvesting photons from electrons.
But that starts by getting more electrons out of the power source.The better the injector is at that, the more powerful a beam results, even presuming that the engineers can’t keep finding efficient ways of getting their photons. Walking into a conference room, Saulter is still stunned. He figured he’d just wind Hernandez up by putting the project’s ultimate goal in his colleague’s face. “I had no idea he’d get up to that today.”
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