After years of testing, the Active Denial System -- the pain ray which drives off rioters with a microwave-like beam -- could finally have its day. The Army is buying five of the truck-mounted systems for $25 million. But the energy weapon may face new hurdles, before it's shipped off to the battlefield; a new report details how the supposedly non-lethal blaster could be turned into a flesh-frying killer. The announcement arrives on the same day as a new report from less-lethal weapons expert Dr. Jrgen Altmann that analyzes the physics of several directed energy weapons, including Active Denial, the Advanced Tactical Laser (used as a non-lethal weapon), the Pulsed Energy Projectile (a.k.a. Maximum Pain" laser) and the Long Range Acoustic Device (a.k.a. "Acoustic Blaster"). Dr. Altmann describes the Active Denial beam in some detail, noting that it will not be completely uniform; anyone unlucky enough to be caught in the center will experience more heating than someone at the edge. And perhaps more significant is his thorough analysis of the heating it produces -- and the cumulative effect if the target does not have the chance to cool down between exposures. In U.S. military tests, a fifteen-second delay between exposures was strictly observed; this may not happen when the ADS is used for real. "As a consequence, the ADS provides the technical possibility to produce burns of second and third degree. Because the beam of diameter 2 m and above is wider than human size, such burns would occur over considerable parts of the body, up to 50% of its surface."