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

Presently available atmospheric pressure plasma sources of reactive radicals, ions or intense VUV/UV radiation for materials processing, treatment of toxic waste and removal of surface contamination use arc discharges (DC or low frequency), corona or rf discharges, have too small a volume or their volumetric efficiency is too low, and operate at too high a neutral gas temperatures for many sensitive AF applications. Stevens Institute of Technology and ISSI under a phase I STTR have investigated novel discharge configurations and excitation schemes to obtain maximum radical production and UV radiation intensity in plasmas. Initial measurements of UV radiation output for various gases and gas mixtures were performed and the production of O-atoms, as an example of a radical of interest, was measured spectroscopically. Under the proposed phase II effort the production of O and H-atoms and other radicals of interest such as OH will be optimized for volume scale-up by optimum power conditioning, discharge configuration and gas composition. Methods to accurately quantify the radical production will be developed. Larger area sources using newly developed high speed, high current switches will be investigated for flux scaling of both radicals and VUV/UV radiation.