Sizing charged particles by phase Doppler anemometry.

Abstract

Phase Doppler anemometry (PDA) is one of the most popular optical techniques used to measure particle sizes. The configuration of PDA layout is important for accurate measurement. In this paper, considering the fact that particles are very likely charged due to many reasons, the selection of PDA layout parameters for measuring charged particles is studied. Effective regions in the receiver's configuration parameter plane are found for charged particles. When parameters are selected from the effective regions, the phase-diameter curves of the PDA are linear, which satisfies the requirement of the working principle of PDA for measuring particle diameter. It is found that the scattered power of charged particles is attenuated, and the attenuation only has small oscillation with the variation of particle diameter and is mainly dominated by the surface conductivity, a phenomenological parameter for describing net surface charges carried by particles. A method is proposed to identify charged particles as well as their surface conductivities.