A DMA-Train for precision measurement of sub-10nm aerosol dynamics

Abstract

Measurements of aerosol dynamics in the sub-10ĝ€nm size range are crucially important for quantifying the impact of new particle formation onto the global budget of cloud condensation nuclei. Here we present the development and characterization of a differential mobility analyzer train (DMA-Train), operating six DMAs in parallel for high-Time-resolution particle-size-distribution measurements below 10ĝ€nm. The DMAs are operated at six different but fixed voltages and hence sizes, together with six state-of-The-Art condensation particle counters (CPCs). Two Airmodus A10 particle size magnifiers (PSM) are used for channels below 2.5ĝ€nm while sizes above 2.5ĝ€nm are detected by TSI 3776 butanol-based or TSI 3788 water-based CPCs. We report the transfer functions and characteristics of six identical Grimm S-DMAs as well as the calibration of a butanol-based TSI model 3776 CPC, a water-based TSI model 3788 CPC and an Airmodus A10 PSM. We find cutoff diameters similar to those reported in the literature. The performance of the DMA-Train is tested with a rapidly changing aerosol of a tungsten oxide particle generator during warmup. Additionally we report a measurement of new particle formation taken during a nucleation event in the CLOUD chamber experiment at CERN. We find that the DMA-Train is able to bridge the gap between currently well-established measurement techniques in the cluster-particle transition regime, providing high time resolution and accurate size information of neutral and charged particles even at atmospheric particle concentrations.