Ion Densities and Particle Charges for Alpha Ionization in an Aerosol Atmosphere: Columnar Recombination Corrections |
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Authors: | Y. S. Mayya W. Holländer |
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Affiliation: | Fraunhofer Institut für Toxikologie and Aerosolforschung , Nikolai-Fuchs-Str. 1, D-30625, Hannover, Germany |
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Abstract: | Ionization by alpha sources in an environment containing small aerosol particles is of interest in aerosol neutralizes, particle chargers and atmospheric electricity. It is known that the conventional ion-balance equation is inadequate in describing the bulk ion densities for alpha sources in view of the columnar recombination process. An earlier self-consistent formulation to include this effect is extended to the case of unequal ionic mobilities and the consequent asymmetric charging of particles. Calculations for medium (Radon-222) and low (Thorium-232) energy sources commonly encountered indicate that the columnar recombination corrections lower the ion densities and the particle mean charges by a factor of about 2 for weak sources (strength < 103 ions cm?3 s?1) and by a factor of 1.2 for strong sources (strength = 109 ions cm?3 s?1). The paper presents a detailed study of the dependence of the correction factors as a function of particle concentration and the strength of the alpha sources. |
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