dsinc writes "Wired's Spencer Ackerman voluntarily subjected himself to what the U.S. military calls the Active Denial System, an energy weapon commonly known as the 'Pain Ray' that turns electricity into millimeter wave radio frequency and blasts targets with heat. He describes it thus: 'When the signal goes out over radio to shoot me, there’s no warning — no flash, no smell, no sound, no round. Suddenly my chest and neck feel like they’ve been exposed to a blast furnace, with a sting thrown in for good measure. I’m getting blasted with 12 joules of energy per square centimeter, in a fairly concentrated blast diameter. I last maybe two seconds of curiosity before my body takes the controls and yanks me out of the way of the beam.'"
The device has been tested now on over 11,000 people, with only two serious injuries to show for it. However, the device has limitations: rainy weather decreases its effectiveness, and its "boot-up" time is 16 hours, making it useless for breaking up unexpected, impromptu mobs.