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Neutralizing the world's most deadly killers

DOE/Los Alamos National Laboratory : 03 June, 2007  (Technical Article)
The Department of Energy's Los Alamos National Laboratory scientists have developed a method for neutralizing some of the world's most deadly killers, chemical and biological warfare agents. Using a newly developed Atmospheric Pressure Plasma Jet, workers can quickly decontaminate areas tainted with chemical or biological weapons. The process uses electrically charged helium and oxygen gas to create a chemically reactive spray that destroys killer agents on contact.
Gary Selwyn, lead scientist of the Los Alamos Atmospheric Pressure Plasma Jet development team said, 'Biological and chemical warfare agents come in many forms. They can be spore-forming bacteria like anthrax, vegetative bacteria like bubonic plague and E. coli, viruses like small pox and yellow fever, or even biotoxins like ricin. Bacterial spores like anthrax are often considered the most difficult to decontaminate because they spread so easily and are hard to kill. Chemical warfare agents are primarily blister agents like mustard gas, nerve agents like sarin, or choking agents like phosgene. The most persistent of these are blister and nerve agents, but they can all be deadly. Our tests show the APPJ can quickly decontaminate all these.'

In the past, decontamination was a wet and dangerous process using bleaches or decontamination solutions. Decontamination solutions were often corrosive to materials like metals, plastics, rubber, leather, and, of course, human skin. Furthermore, the solutions could not be used on sensitive electronic equipment and the decontamination of affected areas often required long exposure times, typically 30 minutes or more, to be fully effective. Even the newest bio-chem decontamination foam sprays being developed today are liquid-based and can short out and damage sensitive electronics, like computers and avionics.

To create the APPJ, helium, mixed with small amounts of oxygen, flows between an outer, grounded, cylindrical electrode and an inner, coaxial electrode. These electrodes create an electrical field that pulls off certain electrons to create an ionized gas, or plasma. The loose ions and electrons in the plasma boost other gas molecules in the tube into a metastable state which survive long enough to exit through a nozzle and reach a surface several centimeters away. When the jet flow strikes the contaminated surface, the stream of metastable gas molecules destroys the biological or chemical contaminants, essentially 'burning' them at low temperatures, less than 175 degrees Celsius, without damaging the underlying surface. Because the metastable molecules only live for a fraction of a second before returning to ordinary, breathable helium and oxygen, the process is environmentally safe. Contaminants are suctioned off by a vacuum attachment near the nozzle and concentrated in a small filter.

The APPJ has been tested successfully against a broad spectrum of surrogate chemical and biological agents. Surrogate agents are similar in nature to the actual chemical or biological warfare agents, but are safer for researchers to handle and study. Tests at Los Alamos show the plasma jet capable of destroying 10 million deadly anthrax spores in as little as 30 seconds.

Future research will be toward reducing the jet's temperature, to make it more suitable for personnel decontamination, and making the unit portable. It will be designed to mount on a mobile platform, such as a Humvee, light truck or trailer, which could carry a generator, gas cylinders, air compressor, and associated equipment necessary to power one or more APPJ units. An even smaller unit may be developed in backpack form, resembling a large fire extinguisher in size and weight.
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