| Abstract: | Expansion flows from different kinds of nozzles (pipe, orifice) into the specimen chamber of a scanning electron microscope (JSM 50A, JEOL, Tokyo) were imaged by means of a transmitted electron detection device using its dark field mode of operation. The experimental videosignal distribution has been numerically transformed in order to get particle number density distributions. Absolute quantification using a thin known foil target yields reasonable particle number densities. The experimental investigation of a nonstationary gaseous microjet ejected from a circular orifice (20 μm in diameter) in the wall of a closed vessel (6 cm3 volume) provides for another estimation of the particle number density at an arbitrarily selected point on the microjet axis. |
