I once was curious enough to put a finger above a hole in my microwave oven. The result? A pleasant heat wave, similar to that of opening a oven door, hits you. Now imagine this feeling but instead of a pleasant heat wave, a burning sensation.
This is the weapon that is expected to enter service in 2010 mainly a crowd disperser. It uses powerful microwaves at 95 GHz, that pass through your clothes without setting them on fire, and heat the water molecules of which your body is formed. The microwaves are not strong enough to cause severe burns, but rather to give the nerves under your skin a touch of pain, at a relative temperature of 50 degrees Celsius.
The heat-beam is fired from a large dish which sits on top of a Humvee. With an effective range of 500m, it can cause panic on protesters further away than any non-lethal weapon in service so far.
The system is named by the US military as the Active Denial System or ADS. Another version of this has already been delivered to the U.S. Air Force, called the ADS2, which is bigger, resists to harsher environments and is generally better suited for war theaters.
Below are two videos. The first is of a reporter who offered to be a guinea pig at the demonstration, and the second video is a CNN coverage of the unveiling.