SIMULTANEOUS MEASUREMENT OF AEROSOL-PARTICLE CHARGE AND SIZE DISTRIBUTIONS

A new procedure has been developed for the analysis of aerodisperse systems to determine electric charge distributions of different sized particles. The suggested method involves the selection of particles having a specific mobility in an electric field from an ensemble of aerosols. For this purpose a differential mobility analyser (DMA) is used. An aerosol size analyser is used to register the size distribution of the sampled particulates. Similar measurements are performed for different high voltages on the DMA electrodes. Then the measured results are subject to mathematical processing to obtain a two-dimensional particle size and charge distribution. The device allows the analysis of aerodisperse systems containing particles ranging from 0.3 to 10-mu-m in diameter with charges ranging from unity to 10(5) elementary charges (of both signs). To illustrate the procedure, this paper presents the results of measurements of particle charge distributions for different size fractions under different conditions of aerosol charging. The results are in good agreement with known theoretical concepts.