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2012 News Releases

Longwood chemist does research helping Air Force build better bombs

November 5, 2012

Dr. Keith Rider
Dr. Keith Rider

A Longwood University chemist spent the last year helping the Air Force build better bombs.

Dr. Keith Rider participated in a research project that is part of the Air Force Research Laboratory's effort to find lighter, more energy-dense energetic materials, including propellants, pyrotechnics and explosives. Rider's project involved making nanometer-sized metallic particles as additives to increase the energy density of an explosive.

Rider spent the 2011-12 academic year on sabbatical working at the High Explosives Research and Development facility (HERD) at Eglin Air Force Base in Florida. The HERD, whose motto is "Molecules to Munitions," is part of the Air Force Research Laboratory Munitions Directorate and is the only Air Force facility that develops explosives.

"You always want more bang for your buck," said Rider, whose research, under the auspices of the National Academy of Sciences, was conducted through the Research Associateship Program of the National Research Council (NRC). He received a grant from the NRC after a proposal he submitted was reviewed and approved by a panel of experts.

Compared with nuclear explosives, conventional explosives have a relatively low energy density, and there have been few improvements since the invention of TNT in the 19th century. Many metals can release large amounts of heat as they oxidize, which makes them an attractive, energy-dense additive for conventional explosives, but two critical technological problems must be overcome before metallic additives can be widely used, said Rider.

"First, metal particles usually oxidize spontaneously by reaction with air, and, if a significant fraction of each particle is oxidized, the amount of energy that is released during the explosion is reduced. Second, metal oxidation reactions are significantly slower than the decomposition reactions that drive conventional explosives. For metals to react quickly enough to be useful, the particles must be extremely small so that the oxidation reaction can take place simultaneously for most of the material in the particles. Researchers at the Air Force Research Laboratory Munitions Directorate are developing a method for producing nanometer-sized metal particles that may be able to address both problems."

Rider's work involved several experiments daily in a machine called the Superfluid Helium Droplet Assembler (SHeDA), which aids advanced munitions research by synthesizing energetic material nanoclusters. This the first machine of its kind used by the Department of Defense, one of only a handful of such machines in the world (the others are used by universities) and the only one designed for producing metal particles in large quantities.

As part of his research experience, Rider spent a week in October 2011 in the New Mexico desert where he attended a seminar on explosives safety at a facility located on 40 square miles of uninhabited desert wilderness-a perfect place for blowing things up.

"For the grand finale on the last day, they built a small shed and parked a Chevy Suburban next to it, then put 300 pounds of ANFO-ammonium nitrate fuel oil-in the back seat and blew it up. It chopped the Suburban into little pieces and was loud enough that you could feel it. It felt like someone squeezing your chest."

Rider has published several articles on his research and is the principal author of "Thermochemical Measurements of a Magnesium-Perfluoropolyether Pyrolant," which has been submitted for publication in Propellants, Explosives, Pyrotechnics. His research was supported by the Air Force Office of Scientific Research. He hopes to continue his magnesium/Fomblin research using Longwood students.