Separation of Dust Particles in a Plasma Trap in the Area of Narrowing of the Current Channel

The selection of dust particles in a plasma trap in the region of a double electric layer in a glow discharge formed by a sharp narrowing of the current channel created by introducing a dielectric insert into the discharge has been studied. The theoretical model of the formation of a double electric layer with a wider cross-section on the cathode side, available in the literature, has been analyzed. It has been shown that under typical conditions for dusty plasma in a helium discharge, the potential jump does not exceed 12 V. The selection of polydisperse quartz particles at low discharge currents has been experimentally studied; it has been found that there is a weak dependence of particle size on pressure. Under experimental conditions, the size of dust particles was about 4 μm. The use of dust particles as a kind of “dust probes” based on the estimation of the balance of vertical forces has showed the correspondence between the conclusions of the discussed theory and the experimental results.