http://en.wikipedia.org/wiki/Active_Denial_System
The Active Denial System (ADS) is a non-lethal, directed-energy weapon developed by the U.S. military.[1] It is a strong millimeter-wave transmitter used for crowd control (the "goodbye effect"[2]). Informally, the weapon is also called pain ray.[3] Raytheon is currently marketing a reduced range version of this technology.[4]
The ADS is currently being considered for deployment in the Iraq War. ADS has also been present at various public events in the United States. It is unclear if the government has sought any authorization to deploy the weapon at home or did so without public input.[5]
Contents
[hide]
* 1 Effects
* 2 Demonstration
* 3 Controversy
* 4 Silent Guardian
* 5 Contracts
* 6 See also
* 7 References
* 8 Further reading
[edit] Effects
The ADS works by directing electromagnetic radiation, specifically, high-frequency microwave radiation, at a frequency of 95 GHz[6] (a wavelength of 3.2 mm) toward the subjects. The waves excite water molecules in the epidermis to around 130 °F (55 °C), causing an intensely painful sensation of extreme heat. While not actually burning the skin, the burning sensation is similar to that of a light bulb being pressed against the skin.[6] The focused beam can be directed at targets at a range of just under half a kilometer, or about 550 yards.[7] The device can penetrate thick clothing, although not walls.[7]
At 95 GHz, the frequency is much higher than the 2.45 GHz of a microwave oven. This frequency was chosen because, due to the stronger absorption of water at those frequencies, they penetrate the skin to a depth of less than 1/64 of an inch (0.4 mm),"[8] which is where the nerve endings are located.
A spokesman for the Air Force Research Laboratory described his experience as a test subject for the system:
"For the first millisecond, it just felt like the skin was warming up. Then it got warmer and warmer and you felt like it was on fire.... As soon as you're away from that beam your skin returns to normal and there is no pain."
Electromagnetic radiation cannot pass through a conductor, so the effect can be shielded by a a conductive mesh or foil which forms a Faraday cage around the target.
While the effects can be unpleasant, ADS has undergone extensive testing since its inception more than 12 years ago. Research into whether or not the device will cause long term health effects has been inconclusive. Many aspects of the research are classified, making independent evaluation impossible. The beam is designed only to affect an individual for a short moment, due to safety presets and features, but these settings can be overridden by the operator.[9] According to public release, there have been over 10,700 "shots" by ADS.[10]
The ADS is currently only a vehicle mounted weapon, though U.S. Marines and police are both working on portable versions.[citation needed]
video:
http://www.youtube.com/watch?v=CpjxjLRKqw8
http://www.youtube.com/watch?v=l4qNG8OrJ0M&feature=related
http://www.youtube.com/watch?v=4D0U7mfsa9Y