The Magnification Factor For Sodium Chloride Liesegang Circles Established With An Aerosol Centrifuge

Sodium chloride particles deposited on a gelatin film containing silver nitrate form in a humid environment clearly visible dark brown reaction spots (Liesegang circles) after development in u.v.-light. The size of these reaction spots depends on the mass of NaCl in the particles. To establish the spot size vs particle size relation, particles produced by nebulising NaCl-solutions and sea water were sampled in an aerosol centrifuge. The location of deposition yields the aerodynamic diameter of the particle, and the spot size is measured microscopically. In this way the spot size vs aerodynamic diameter relation is established experimentally in the so far unexplored aerodynamic diameter range between 0.5 and 2.0 μm. © 1976

Radiometric force in dusty plasmas

A radiofrequency glow discharge plasma, which is polluted with a certain number of dusty grains, is studied. In addition to various dusty plasma phenomena, several specific colloidal effects should be considered. We focus on radiometric forces, which are caused by inhomogeneous temperature distribution. Aside from thermophoresis, the role of temperature distribution in dusty plasmas is an open question. It is shown that inhomogeneous heating of the grain by ion flows results in a new photophoresis like force, which is specific for dusty discharges. This radiometric force can be observable under conditions of recent microgravity experiments.Comment: 4 pages, amsmat