Inference of Electron-Ion Recombination Coefficients from Microwave Afterglow Measurements Employing Microwave Heating of Electrons

The rates of recombination of NO('+) and O(,2)('+)(.)O(,2) dimer ions with electrons as a function of electron temperature have been deter- mined using a microwave-afterglow/mass -spectrometer apparatus employing microwave heating of electrons. The recombination rates for these ions are of importance for modeling the upper atmosphere. The electron temperature T(,e) was found to vary spatially throughout the plasma and an improved data analysis method had to be developed. This data analysis method was used in the present studies to determine the recombination rate coefficient (alpha). The results of the recombination studies of NO('+) ions with. electrons as a function of electron temperature can be represented by the simple power law dependence. (DIAGRAM, TABLE OR GRAPHIC OMITTED...PLEASE SEE DAI). over the electron temperature range 295 K (LESSTHEQ) T(,e) (LESSTHEQ) 4500 K. This measurement is in agreement with other experimental determinations of (alpha)(NO('+)). The results of the recombination studies of O(,2)('+)(.)O(,2) dimer ions with electrons can be expressed by the power law. (DIAGRAM, TABLE OR GRAPHIC OMITTED...PLEASE SEE DAI). over the range 143 K (LESSTHEQ) T(,e) (LESSTHEQ) 5500 K. This is the first measurement of the O(,2)('+)(.)O(,2) dimer ion recombination rate coefficient at elevated electron temperatures. The room temperature value of the recombination coefficient is consistent with room temperature values for other dimer ions, i.e. (TURN)10('-6) cm('3)/sec. Also, a comprehensive review of previous microwave afterflow studies was made to determine the possible effect of the non-uniformity of the electron temperature on the data analysis of those experiments. It is found that the essential conclusions of most (but not all) of the previous afterglow studies are still valid, but that the interpretation of the data should be modified.