INFLUENCE OF COULOMB AND IMAGE FORCES ON COMBINATION IN AEROSOLS

Abstract

The effect of electrostatic image forces on the combination of small ions and charged aerosol nuclei is examined. Collision enhancement factors are derived for small ions with constant velocity. Evaluations are then made taking into account the Maxwellian velocity distribution of the small ions. Collision treatment inside the limiting sphere and diffusion treatment outside are com bined by equating the ion flux on the two sides. The resultant combination coefficients give good agreement with the Boltzmann Distribution Law, for radii greater than approximately 1 x 106 cm. These coefficients give Whipple type differences which vary with the nucleus size and which are less than the Whipple difference 4iww. For very large nuclei the difference is 0O5 (47eMW), for atmospheric size nuclei 0 75 (4iuxo) and for very small nuclei 0 9 (4urex). I. INTRODUCTION Keefe and Nolan (1961) examined the effect of electrostatic image forces on the combination of small ions and uncharged nuclei. The present paper extends this examination to the combination of small ions and charged nuclei. The volume surrounding a nucleus is divided into two regions, as indicated in Fig. 1, an inner volume where the collision treatment is valid and an outer ->RL.. / COLLISION DIFFUSION --job.- 6 n ~~~f(R) H _ < 11 )~~~~~~~~~-w n (cxD R