It may seem like something straight out of science fiction, but the U.S. Army is developing a defense system that uses an expanding ball of plasma to create an array of midair explosions that can stun or confuse an enemy while simultaneously creating force deflection that could deflect incoming explosives or projectiles. The idea is still far from completion, but the science behind it is simple: A laser pulse creates a ball of plasma, a type of matter that has properties of a super-hot gas, and as the ball expands, the machine uses a second laser pulse to create a shockwave inside the ball of plasma, forcing it to rapidly expand outward. The Army is calling the high-tech shield the Plasma Acoustic Shield System (PASS).

The PASS will be combined with a siren and speaker system to create loud alerts and a flashing light system that will not only create the plasma shockwave but also provide intense sound and light to confuse and disorient enemies in its path, and other systems that rely on sight or sound to operate. The Army expects the system to have a range of about 100 meters.

The PASS requires tremendous power to operate the two lasers required to generate the plasma and shockwave, so until power consumption levels come down, it's unlikely the Army will deploy the PASS in combat. Even so, the eventual goal is to develop a device small enough that an individual can carry it into combat and use it in to either stun and repel enemies or kill them. Currently the PASS is too large for that, and vehicle mounted prototypes are scheduled to be tested late 2008 into 2009. Sorry, sci-fi junkies--this is less of a protective shield that can encase vehicles and buildings and more of a direct-energy weapon that can be used against other targets. [ via NewScientistTech ]