Scientists this spring plan to launch a particle beam accelerator on a 10-minute suborbital flight to help study whether devices that generate neutral particle beams might be useful in space-based weapons.

Electrically charged particle beams would be bent by the Earth's magnetic field lines, but neutral beams should fly straight, according to scientists who have been working on such devices for anti-missile defense since 1975.The launch of a 40-foot Aries rocket from White Sands Missile Range carrying a 10-foot-long particle accelerator will be the first test in space by the Los Alamos National Laboratory scientists.

At altitudes above 75 miles, the accelerator will shoot 1,200 pencil-shaped bursts of hydrogen atoms toward the ground. The beams will cause the air along their paths to glow so they can be tracked through the night sky. However, the beams won't reach the ground. Below 75 miles, they collide with thicker air, become electrically charged and are deflected by the magnetic fields.

Forty scientists, engineers and technicians have been working on the experiment, called Beam Experiment Aboard a Rocket, or BEAR. The team proved accelerators could be made small enough to be boosted by a rocket, at least for a low-energy experiment. The payload, including the accelerator, data-gathering devices and means of controlling the rocket's altitude, is 44 inches in diameter, less than 24 feet long, and weighs 1 1/2 tons.