ION DENSITIES AND PARTICLE CHARGES FOR ALPHA-IONIZATION IN AN AEROSOLATMOSPHERE - COLUMNAR RECOMBINATION CORRECTIONS

Ionization by alpha sources in an environment containing small aerosol particles is of interest in aerosol neutralizers, particle chargers a nd atmospheric electricity. It is known that the conventional ion-bala nce equation is inadequate in describing the bulk ion densities for al pha 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 chargin g of particles. Calculations for medium (Radon-222) and low (Thorium 2 32) energy Sources commonly encountered indicate that the columnar rec ombination corrections lower the ion densities and the particle mean c harges by a factor of about 2 for weak sources (strength < 10(3) ions cm(-3) s(-1)) and by a factor of 1.2 for strong sources (strength appr oximate to 10(9) ions cm(-3) s(-1)). The paper presents a detailed stu dy of the dependence of the correction factors as a function of partic le concentration and the strength of the alpha sources.