Fundamental Study of Aerosol Charging by Ions and Free Electrons in the Transition and Free-Molecule Regimes

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9304152 Pui The proposed study deals with experimental and theoretical investigations of aerosol charging by ions and free electrons in the transition and free-molecule regimes. It is aimed to resolve existing discrepancies between theories and experiments. Aerosol charging and the subsequent manipulation of the particles in an electric field are effective means of measuring, classifying and collecting them. The project will first focus on developing an aerosol charger of low particle-loss, capable of operating under vacuum and in high purity gases. It will be followed by experimental studies of aerosol charging by ions and free electrons. Aerosol charge distributions will be measured. This method of testing charging theories is more sensitive than the traditional charged fraction measurement. A numerical solution to the Boltzmann collision equation will be obtained to compare with the existing theories and with data obtained. The results of this study should provide a better understanding of fundamental transfer processes and the needed knowledge base towards improving the collection efficiency of electrostatic precipitations in the air pollution control industry, measuring and classifying nanometer particles in the materials industry, and controlling particulate contaminants in plasma reactors in the microelectronics industry. ***