Articles | Volume 9, issue 7
Atmos. Meas. Tech., 9, 2977–2988, 2016
Atmos. Meas. Tech., 9, 2977–2988, 2016

Research article 14 Jul 2016

Research article | 14 Jul 2016

Operation of the Airmodus A11 nano Condensation Nucleus Counter at various inlet pressures and various operation temperatures, and design of a new inlet system

Juha Kangasluoma1, Alessandro Franchin1, Jonahtan Duplissy1, Lauri Ahonen1, Frans Korhonen1, Michel Attoui1,2, Jyri Mikkilä1, Katrianne Lehtipalo1,3, Joonas Vanhanen4, Markku Kulmala1, and Tuukka Petäjä1 Juha Kangasluoma et al.
  • 1Department of Physics, P.O. Box 64, 00014, University of Helsinki, Helsinki, Finland
  • 2University Paris Est Creteil, University Paris-Diderot, LISA, UMR CNRS 7583, Paris, France
  • 3Paul Scherrer Institute, 5232 Villigen PSI, Switzerland
  • 4Airmodus Ltd., Pietari Kalminkatu 1 F 1, 00560 Helsinki, Finland

Abstract. Measuring sub-3 nm particles outside of controlled laboratory conditions is a challenging task, as many of the instruments are operated at their limits and are subject to changing ambient conditions. In this study, we advance the current understanding of the operation of the Airmodus A11 nano Condensation Nucleus Counter (nCNC), which consists of an A10 Particle Size Magnifier (PSM) and an A20 Condensation Particle Counter (CPC). The effect of the inlet line pressure on the measured particle concentration was measured, and two separate regions inside the A10, where supersaturation of working fluid can take place, were identified. The possibility of varying the lower cut-off diameter of the nCNC was investigated; by scanning the growth tube temperature, the range of the lower cut-off was extended from 1–2.5 to 1–6 nm. Here we present a new inlet system, which allows automated measurement of the background concentration of homogeneously nucleated droplets, minimizes the diffusion losses in the sampling line and is equipped with an electrostatic filter to remove ions smaller than approximately 4.5 nm. Finally, our view of the guidelines for the optimal use of the Airmodus nCNC is provided.

Short summary
The paper describes technical aspects of using the Airmodus A11 nCNC at various inlet pressures and how temperature selection affects the performance of the instrument. We also present a sampling box to minimize the inlet losses and make use of the instrument more convenient.