Very Long DMA for the Generation of the Calibration Aerosols in Particle Diameter Range up to 10 μm by Electrical Separation

摘要

For the generation of the quasi-monodispersed standard (calibration) aerosols, the electrical separation of particles from the aerosol with wide size spectrum can be used in quite a wide particle diameter range, from some nanometers up to approximately 10 micrometers. A solution to the problem of multiple elementary charges on the particles, degrading the quality of the separated aerosol in the range of large particles, was proposed in a separate paper. In this paper, a unique very long DMA for the separation of such large particles is described, together with a technology for its manufacturing. Effects of some possible non-ideal properties of the DMA, arising from the manufacturing techniques used, are investigated both theoretically and experimentally; no significant distortions of the DMA transfer function were found. A new method for the experimental determination of the transfer function of the DMA, using Microsphere Size Standards (highly monodisperse polystyrene aerosols) is described. It was confirmed, that electric wind can be a distortion factor of the DMA transfer function and the continuous tracking of it, when separating standard aerosols, is necessary. Effect of gravity on the DMA transfer function is also discussed.