Variation of SMPS data in the unsteady particle concentration condition

Abstract

Scanning Mobility Particle Sizer (SMPS) is a useful instrument to measure the size distribution of aerosol and nano-particles. It is composed of a differential Mobility Analyzer (DMA) to classify particle sizes according to an exponential voltage change and a Condensation Particle Counter (CPC) to measure particle concentrations for the fractionated particle sizes. The SMPS usually requires about 120 s for a measurement. However, an uncertain particle-size distribution will be measured by the SMPS if the aerosol concentration is noticeably changed with time during scanning. Therefore, in the present study, we numerically analyze the SMPS measurement results for an unsteady aerosol concentration, and compare them with the experimental data.