Development and preliminary testing of a device for electrostatic classification of submicron airborne particles

Abstract

A practical apparatus was developed for electrostatic size classification of aerosol particles of 0.1 to a few microns in diameter. The aerosol, surrounded by a sheath of clean air, is charged by passing it closely over an intense positive discharge at high speed. It enters as a fine filament at 1 m/sec into an electrostatic field between parallel plates. Charging rates several times above those predicted by conventional theory permitted good resolution. A high natural charge on the aerosols had an adverse effect on classification. Various aerosols were examined, and results of practical significance were obtained. With salt aerosols, strong, higher-order Tyndall spectra were observed from the classified deposit. © 1961 The American Institute of Physics.