A corona-discharge-based aerosol neutralizer designed for use with the SMPS-system

The widely used scanning mobility particle sizer (SMPS) for measuring submicron particles uses radioactivity to charge aerosol particles to a known charge distribution. Because of numerous restrictions and safety issues concerning radioactive sources, corona-discharge-based neutralizers are an attractive alternative. The newly developed electrical neutralizer consists of an aerosol chamber with an AC electrical discharge. Combining small residence times, high ion concentrations, small electric field strengths, discharge in the aerosol chamber itself and an automatic regulation of the ion input results in a very effective neutralizing device. Experiments with an initially uncharged aerosol have shown that charging of submicron particles to the bipolar equilibrium charge distribution was possible for volumetric flow rates of up to 1.5 L/min and concentrations of at least View the MathML source5×1061/cm3. Particle loss (>3 nm) and particle production (>3 nm) were not observed.