In the 1950s, movies featured space aliens firing ray guns at planet Earth. Wielding lethal hand-held ray guns, martians invaded our cities, but this was all science fiction. That was then. This is now.
The Army's new Active Denial System (ADS) is essentially a ray gun that zaps its target with intense heat, moving potential threats out of the way without injury or lasting effects, according to Marine Corps. Col. Kirk Hymes, director of the Joint Non-Lethal Weapons Directorate. “This does not incapacitate them,” he says. “This pushes them back and out of the way. One thing we are trying to get across is that this technology is not a microwave with the ability of cooking somebody from the inside out.”
The weapon shows how sensitive the military has become to killing non-combatants and innocent bystanders. While the non-lethal ADS is backed up by myriad ways to kill, it does the job without inviting the intractable hatred when innocent members of a family are killed.
“I'm an artilleryman. My training is to be lethal,” says Col. Hymes. “But our intent (with the ADS) is to escalate beyond shouting, but short of shooting.”
The ADS technology, featured on the TV news program “60 Minutes” several weeks ago, was 15 years in the making, says Diana Loree, a Ph.D. in electrical engineering at the Air Force's Research Lab. Directed Energy Directorate at Kirtland AFB in Albuquerque. “It took several years to find the safe, but effective parameters. You work at different frequencies and powers,” she says. “You're basically stepping back and forth advancing safety and effectiveness.”
The challenge was finding the correct frequency to create a “repel effect,” according to Stephanie Miller, a technology adviser at the Air Force Research Lab. at Brooks City-Base in San Antonio where the initial research was done.
“We had an idea and designed experiments to determine whether or not we could make our idea a reality on a small scale. We conducted some initial experiments on what might be appropriate parameters for a larger system. We turned our information over to Diana, who worked on what would make a useful tactical weapon,” she says.
The beam's energy heats water molecules in the skin, causing them to vibrate. The heated molecules interact with the skin's top 1/64th of an inch. “The nerves are about that level and you move out of the way very quickly,” says Miller, adding that precise figures on how much energy to make this happen are classified.
“The difference is to (balance) repelling and energy without causing an injury like a blister or eye irritation. It's all about heat. We've done a lot of research. There's no cancer, reproductive problems or birth defects. That's why it took so long to get here,” says Miller.
At the heart of the ADS is a 100 kW ultra-high radio frequency transmitter at whose core sits a gyrotron to turn electricity into a 95 GHz radio frequency beam. For comparison's sake, an FM radio transmitter customarily operates at 50 kW. The gyrotron's ability to focus heat has made it useful in a variety of high-energy physics applications.
The ADS gyrotron is made by CPI Inc. of Palo Alto, CA. Raytheon is the technology integrator and while the unit costs $10 million to build, the price should go down if it heads into volume production at some point. What's more, the technology could be leveraged in other form factors.
“It could be smaller, lighter and cheaper to build. Could it be like the “Star Trek Phaser” that freezes somebody? I would not put any limitation on any scientists in this great country of ours,” says Col. Hymes.
Loree is a bit more realistic. “We know we could make it smaller by 25 percent in volume and weight and still keep the same range and main characteristics. As the war fighters begin to use it, they will figure out what they need. The hand-held size with the battery and all is not in the near future. It's hard to go from Humvee size down to a hand-held.”
The ADS fires off 4 sec bursts which travel at the speed of light. Inside the cavity of the gyrotron, electricity interacts with a magnetic field to create the radio beam at the correct (and presumably harmless) frequency. The transmitter is 50 percent efficient, Loree adds. By that, she means half the electricity fed into the gyrotron gets focused into the beam and the other half get dissipated as heat by a closed loop de-ionized water cooling system. “For every two watts, I get one watt for the RF beam,” she says.
The aiming device is nothing more than a series of bore-sighted cameras that peep through three holes in the mechanism's offset fed cassegrain antenna so the operator can look directly down the center of the beam to the target. Infrared capability can be applied for night use.
“It's very simple to operate. The operator's display has a cross hair on it so he can zoom in on the target. Then he's looking down the middle the beam,” Loree says. The ADS has a specified range of 500m, longer than small arms fire and well “within in the comfort zone” of someone tossing a Molotov cocktail, says Col. Hymes. “It's like firing an (invisible) bullet.”
Two units are currently being tested: one mounted on a hybrid Humvee and another in an armored container. While the Air Force has the lead development, it's up to Col. Hymes to make sure the technology is available to all branches of the military.
“It used to be we had uniformed combatants going against uniformed combatants. Now our war fighters find themselves in peacekeeping missions, humanitarian relief and insurgencies. They need tools to accomplish their mission,” he says. “That bullet in a counter insurgency can be very cost effective if it hits the right target. If it hits the wrong target, it creates more enemies.”
He envisions the Navy using it to ward onlookers and threats away from ships. Or when a crowd rushes a helicopter flying in foodstuffs, an ADS can keep the crowd from getting disorderly.
"We have instances where helicopters had a hard time landing to deliver foodstuffs. Hunger is a pretty motivating factor and if I was senior member of my tribe or clan and I've watched my family die from hunger, I'll do what it takes to get those foodstuffs. How do you non-lethally get them to stand in an orderly fashion so the food can be delivered safely and proportionally and protect those who aren't in a rush? If you can target individuals to stay back, leave the area or form an orderly line, it only takes a couple of individuals to be targeted and it says there's something going on here," says Col. Hymes.
The next step is to test the ADS in an applicable setting like Iraq where sandstorms are frequent and many in the population are hostile to American war fighters. The technology is proven, but now must show itself to be maintainable and durable. The demonstrator will get a full trial starting this summer in Iraq.
"We're very close. Now it has to hold up in a challenging environment," says Col. Hymes.