On the effect of charge recombination on the aerosol charge distribution in photocharging systems

An experimental study has been carried out to determine the aerosol charge distribution through photocharging process. Particle charge distribution was studied in dependency on particle number concentration and irradiation intensity. While highly positively charged aerosols were obtained for particle number concentrations below 5×1011 m−3, approximately symmetrical bipolar charge distributions were measured for number concentrations of about 2×1013 m−3. The theoretical description was made on basis of the previously developed model, which was extended by a term accounting for ion diffusion losses. Theoretical results reflected experimental observations. The necessity of taking into account diffusion discharging of particles by gas ions is determined by a dimensionless factor depending on initial parameters. Since the charge distribution through photocharging becomes a known function of particle and irradiation parameters, a photocharger may be used instead of a neutralizer to produce a defined charge distribution.