Fundamental Studies: Evaporation Rates of Films and Particulate of Explosives from Surfaces and Materials

Essential understandings needed to design methods or technology for determining explosives in specific military grade or improvised explosive bombs depend upon knowledge of elementary properties of explosives and the environmental variables that affect the generation and transport of vapors or particulate from bulk materials. A surprising result of a conference of investigators in November 2008 at the Transportation Security Laboratories was that there are presently neither validated models nor complications of properties of explosives to inform researchers, developers or technical managers in the US and allied nations. In the research program described below, field studies emissions of explosives in realistic amounts and packaging will be supported and supplemented with laboratory studies which provide a first ever set of measurements of evaporative loss under controlled parameters with methods that are repeatable and defensible. The data base envisioned here would be accessible for modeling of bulk behaviors and will be upgradable and backwards compatible with studies for emerging explosive threats. Thus, the work will not be specific to a particular laboratory or set of investigators and instead will be a broadly accessible utility for use throughout the community of scientists and engineers involved in explosives research and development in the US and allied nations. In this work, two teams with particular specialization and proven records of join work are combined to provide a level of experience in explosives manufacture not usually found in academic environments and knowledge of chemical and physical properties of explosives not usually found in industrial venues. Distinctions will be made throughout with mass transport from vapors or particulate. In laboratory studies, the goal will be the determination of evaporation rates under conditions of temperature and pressure under which explosives can be deployed for military or civilian attacks. Bulk studies are designed to provide elementary rate data for both vapors and particulate from actual field trials. The end goal will be libraries of vaporization rates at various temperatures in a highly controlled venue (i.e., a laboratory) and concentrations of explosives in air at distances from realistic devices in actual in-field measurements. The generated models will be validated using field operational parameters. This combination is anticipated to provide a single source document or resource which will be established early in the program and improved or augmented through the studies. Thus, results usable in the community of researchers, developers, and administrators will flow early in the program and not be held until the studies are completed. This concept of a living and open (with limited access) data set should aid and speed the work of others in explosives detection.