Ion Densities and Particle Charges for Alpha Ionization in an Aerosol Atmosphere: Columnar Recombination Corrections

The deposition rate of glass cylinders and dust paper fibers in a turbulent duct flow was studied experimentally. The glass fibers with a minimum diameter of 5 J.lm and the paper fibers with a minimum diameter of 1-20 J.lm and aspect ratios from 4 to 20 were deposited on a flat gold plate. The particle concentration at the test section was measured with the aid of an isokinetic probe in conjunction with a digital image processing technique. An oil lubricant was used on the plate to reduce the effect of particle bounce from the surface The experimental data show that the deposition rate increases with an increase in fiber length and size. For a fixed minimum diameter or a fixed equivalent relaxation time, the deposition rate increases rapidly with fiber aspect ratio. When the equivalent spherical particle relaxation time is used, the deposition rate of the fibers was found to increase only slightly with aspect ratio and resemble those of spherical particles. The measured deposition velocities were in good agreement with the empirical model predictions and previous data.