Abstract
ABSTRACTAccurate measurement of particle size distribution using electrical-mobility techniques requires knowledge of the charging state of the sampled particles. A consistent particle charge distribution is possible with bipolar diffusion chargers operated under steady-state condition. Theoretical steady-state charge distributions for bipolar charging are well established but recent studies have shown that the performance of particle chargers is a strong function of particle size, particle concentration, ion source, and charger operating conditions. Most of these studies have focused on particles smaller than 100 nm and the applicability of these results for particles larger than 100 nm must be investigated. In this study, experimentally obtained singly-charged and doubly-charged fractions are compared against theoretical predictions for particles in the size range of 100 to 900 nm. The experimental results show that the commercial soft X-ray charger performs as theoretically-predicted over the range of ...
Highlights
The size distributions of particles smaller than 500 nm can be precisely measured using electrical-mobility technique (Knutson and Whitby 1975)
The ideal operation of the bipolar charger would result in particles attaining a steady-state charge distribution that would only depend on particle size (Fuchs 1963)
The test particles were positive, singly-charged ammonium sulfate and the particles exiting the bipolar charger were classified by DMA2 operated with a negative polarity high voltage (i.e positively-charged particles were extracted out of DMA2)
Summary
The size distributions of particles smaller than 500 nm can be precisely measured using electrical-mobility technique (Knutson and Whitby 1975). Initial experimental studies of particle charging with radioactive bipolar chargers showed that near steady-state bipolar charge distributions can be achieved with several different radioactive sources (Liu and Pui 1974a; John and Davis 1974; Kojima 1978). Even with a lower activity source (37 MBq 85Kr) and a higher aerosol flowrate (24 l¢min¡1), John and Davis (1974) showed that spherical submicron particles can be brought to near equilibrium charge distribution. Such initial studies demonstrating the robust charging characteristics of custom-built. The experimental determined charge fractions were compared against the predictions of Boltzmann equilibrium charge distribution and the empirical equation of Wiedensohler (1988)
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
