Free air beam in an electric field for determination of the electrostatic charge of powders between 1 and 200 μm

There are a number of charge spectrometers for powders published in the literature. In these devices mainly a laminar air flow with a crosslinked electric field is used for the evaluation of the charge-to-diameter ratio q/d. This paper should show the possibility of a so-called ‘free air beam’ in an electric field for determination of the q/d distribution.