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TIME-OF-FLIGHT AEROSOL BEAM SPECTROMETER FOR PARTICLE SIZE MEASUREMENTS
Citation:
Dahneke, B. TIME-OF-FLIGHT AEROSOL BEAM SPECTROMETER FOR PARTICLE SIZE MEASUREMENTS. U.S. Environmental Protection Agency, Washington, D.C., EPA/600/2-77/229 (NTIS PB276644), 1977.
Description:
A time-of-flight aerosol beam spectrometer (TOFABS) is described. The instrument has been designed and constructed to perform in situ real time measurements of the aerodynamic size of individual aerosol particles in the range 0.3 to 10 micrometers diameter. The measurement method consists of (1) allowing a sample aerosol to undergo expansion through a nozzle into a vacuum chamber, such that each particle acquires a terminal velocity depending on its aerodynamic size, then (2) measuring the terminal velocity by determining the time taken for each particle to traverse a laser beam of fixed width. An experimental calibration curve relating time-of-flight and aerodynamic size, based on the use of polystyrene latex spheres, is shown to be in good agreement with a theoretical calibration obtained from the gas-particle dynamics equations. A comprehensive discussion of the properties and uses of aerosol beams is included as an appendix.