Abstract
The electron-ion recombination coefficients for and ions have been determined by means of a microwave afterglow/mass-spectrometer apparatus. Measurements of electron density decays in helium-hydrogen mixtures are correlated with the decay of mass-identified ion currents to the wall of the microwave cavity. At low partial pressures of hydrogen in the mixture, the ion dominates the ion composition and the ion wall current "tracks" the electron density decay curves. From recombination controlled electron density decay curves, the values /sec are obtained at 205, 300, and 450 K, respectively. At higher partial pressures of hydrogen and low temperatures, where is the dominant ion, the value /sec is obtained at 205 K. The implications of these results concerning ionization levels in the atmospheres of the outer planets and in the intersteller medium are discussed.
- Received 14 March 1973
DOI:https://doi.org/10.1103/PhysRevA.8.413
©1973 American Physical Society