High Flux Radical and Ultraviolet (UV) Generation by Atmospheric Pressure Nonequilibrium Plasmas.

Plasmas have found wide application as sources of reactive radicals and ions for materials processing and treatment of flue gases. Operation at atmospheric pressure obviates the need for a vacuum system. Of the available types of plasma source used todissociate molecular gases at atmospheric pressure are arc discharges, which operate at neutral gas temperatures of up to 10,000 K; corona and dielectric barrier discharges have cooler neutral gas temperatures and are used with larger gas volumes inconventional operating modes. More recently, discharges with a high percentage of a background gas such as helium were successfully operated at atmospheric pressure and under non-equilibrium conditions, producing radicals at low neutral gas temperature.Stevens Institute of Technology and ISSI propose to investigate discharge configurations and excitation schemes to obtain maximum radical production and UV radiation intensity generation without a large amount of background gas. Possible configurationsinclude dielectric barrier discharges with high rep-rate short pulsed excitation and operating with high peak-power, and under highly nonequilibrium conditions, resulting in low neutral gas temperature. Methods will be developed to accurately assessproduction efficiency of radicals of interest, UV intensity and spectral distribution and neutral gas temperature. During a subsequent Phase II program various plasma sources and excitation methods will be evaluated and optimized and tested. Successfuldevelopment of an efficient radical and UV sources operating at atmospheric pressure and low gas temperature will have a multitude of commercial potential. The commercial products foreseen from this SBIR Program are the development of plasma sources forradicals and UV radiation used in material processing, decontamination, and sterilization. Such sources can be used for aerospace and biomedical temperature sensitive materials surface property modification, low temperature decontamination andsterilization, replacing the use of ethylene oxide, formaldehyde and other carcinogenic materials.