QUANTICO, Va. — There's no doubt this oversized ray gun can deliver the heat. The question is, how soon can the weapon, which neither kills nor maims, be delivered to Iraq?

At a rain-soaked demonstration of the crowd-dispersal tool here last month, military officials said one could be deployed early next year. But others still need to be built and undergo more testing before being shipped, a slow-going process at odds with urgent demands from U.S. commanders for the device.

The Active Denial System uses energy beams instead of bullets and lets soldiers break up unruly crowds without guns.

That means fewer civilian casualties, a key ingredient to success in Iraq.

The system just completed a lengthy demonstration phase and is expected to receive a $25 million boost once Congress approves an Iraq war supplemental spending bill. The money will be used to buy five "Silent Guardians," a commercial version of the denial system built by defense contractor Raytheon.

"The systems themselves could be manufactured, more than likely, within 12 months if everything goes according to what Raytheon tells us," said Marine Corps Col. Kirk Hymes, director of the Defense Department's Joint Non-Lethal Weapons Directorate.

To be hit by the invisible beam is to feel the intense heat of a suddenly opened furnace. The instant reaction is to move.

At Quantico, a Marine Corps base south of Washington, a test unit mounted on a Humvee stung reporters and military personnel who volunteered to enter a circle marked by orange traffic cones.

The system is a directed-energy device, although not a laser or a microwave, and can send an invisible beam of waves to a target as far away as 500 yards.

With the unit mounted on the back of a vehicle, U.S. troops can operate a safe distance from rocks, Molotov cocktails and small-arms fire.

The beam penetrates the skin slightly, just enough to cause intense pain. The beam goes through clothing as well as windows, but can be blocked by metal, wood or concrete.