Ionization in oxygen-hydrogen mixtures

Abstract

Current-growth measurements have been made in mixtures of oxygen and hydrogen for a wide range of experimental parameters and mixture concentrations. These mixtures were chosen because hydrogen removes the primary O− negative ions formed in oxygen, through a rapid associative detachment reaction, making the mixture behave as a non-attaching gas. This simplifies the analysis required to obtain ionization coefficients and should give more accurate values of the ionization coefficient for oxygen than can be obtained from measurement in pure oxygen. To check that at any value of E/N the mean energies of the O2-H2 mixtures were not significantly different from those of pure oxygen, the Boltzmann equation for the gas mixtures was solved and the transport properties of the mixture calculated. It was found that for O2-H2 mixtures containing less than 10% hydrogen, the mean energies and the other transport properties were not altered in any significant way. The values of the ionization coefficients obtained in these experiments are in general 30% below earlier published values but are in agreement with some recent current-growth analysis by Wagner (1971) which incorporates detachment and ion-molecule effects.