Active Denial System
ADS (Active Denial System) systems are a new class of nonlethal weaponry using 95 GHz-millimeter-wave directed energy. This technology is capable of rapidly heating a person's skin to achieve a pain threshold that has been demonstrated by AFRL human subject testing to be very effective at repelling people, without burning the skin or causing other secondary effects. The device is an alternative to lethal force.
Source: wired.comAdded: 18 December 2006