Military Laser Gets Ready for Industry

Michael D. Wheeler

The chemical oxygen-iodine laser technology that is the basis of the US Air Force's Airborne Laser aircraft could soon be harnessed for such commercial applications as dismantling and decommissioning nuclear power plants, capital shipbuilding and repair, and even drilling oil wells.

First demonstrated in the 1970s, this technology involves mixing chemicals such as potassium hydroxide and hydrogen peroxide in liquid form with chlorine gas to create excited oxygen. A converging/diverging nozzle and a buffer gas bring this primary flow to supersonic velocities, and a series of chemical reactions excite iodine atoms for lasing.

Now researchers from the University of Illinois and CU Aerospace have assembled a 2-kW chemical oxygen-iodine laser device emitting at 1.3 µm and featuring a nozzle designed for use with a nitrogen gas buffer. The military has traditionally used helium as a buffer -- a far more precious and nonrenewable resource. The university's David Carroll, who directs the research, contends that these alterations could make this technology an attractive alternative to CO₂ and YAG lasers for certain commercial uses.

"The big problem with YAGs -- or any lasers with solid-state crystal rods -- is you get really severe thermal distortions, and that limits power," Carroll said. "When you start to think about CO₂, it can be very powerful, but, at 10.6 µm, it doesn't transmit through a fiber."

The wavelength of a chemical oxygen-iodine laser device, however, is conducive to fiber delivery and can be scaled up to produce more power than a CO₂. Those attributes have led Carroll to lobby for specific uses that could prove cost-effective.

Deactivating nuclear plants

"One of the prime areas where this laser would be useful is in the decontamination of old nuclear facilities. The nuclear hot cells themselves often have stacks of pipes at least a foot wide that would have to be cut through. Since you're talking about a radioactive hot area, you'd much rather go in with a robot," he said.

The chemical oxygen-iodine laser also has demonstrated the ability to cut through many materials, including iron, steel, aluminum and titanium, at a rate three times that of a CO₂. The small spot size of the beam creates minimal dust and fumes, and requires less air filtration than conventional methods.