Neutralizing charged aerosols with radioactive sources

Abstract

Electrically charged aerosol particles reach an equilibrium charge distribution when mixed with positive and negative ions in a time which is inversely proportional to ionic concentration. One way to neutralize the charge on aerosols is to use radioactive sources in a neutralizing chamber. The differential equation governing ionic concentration is analyzed, and approximate solutions are given for various combinations of radioactive source geometry and neutralizing chamber geometry. It is shown that when the range of the radioactive particles emitted by the source is greater than or equal to the chamber dimensions, the ratio of the particle residence time to the characteristic time necessary for neutralization is proportional to the square root of the radioactive source strength, inversely proportional to flow rate, and proportional chamber dimensions to the second power. This ratio is computed for four successful neutralizers and found to be ≳ 10. This analysis should facilitate the design of radioactive neutralizers. © 1973.