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SURFACE EFFECTS IN SEEDED COMBUSTION PRODUCTS,
CORNELL UNIV ITHACA N Y GRADUATE SCHOOL OF AEROSPACE ENGINEERING
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Current-voltage characteristics of a double probe were obtained in the products of combustion of a seeded, atmospheric-pressure, alcohol-air flame. Sodium hydroxide, potassium hydroxide, and cesium chloride were the seed compounds used. An electric current was driven between a pair of small, circular electrodes embedded on the stagnation line of a cylindrical, boron-nitride probe. The temperature of the electrode surfaces could be controlled and measured. Saturation currents were measured which were independent of the electrode temperature below 500K and increased rapidly when the electrode temperature was increased above 500K. The appropriate continuum sheath theory is developed. The theory predicts ion saturation currents and the resistance to the flow of current between the electrodes. The properties of the combustion products are calculated using the measured temperature. Partial dissociation of the seed molecules and electron attachment to the hydroxyl radical are considered. The calculated resistances are in reasonably good agreement with the measured values. The calculated ion saturation currents are three to four orders of magnitude smaller than the measured values. It is concluded that there is electron emission from the electrodes. Author
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