Segmentation of dust particles and spatial distribution of ion density in dusty plasmas

Abstract

In dusty plasmas, dust particles are levitated in balance of electrostatic, ion drag and gravitational forces. These forces depend on the size of the dust particles and discharge conditions. The dust particles can be segmented on the basis of their sizes, i.e., the dust particles are levitated at different positions depending on their sizes. In this work, the dust particles with two different sizes were observed in a plasma and they were divided into segments by changing radio frequency voltage put into the plasma. Meanwhile a numerical model analyzed the forces acting on the dust particles based on ion densities measured in the plasma. The dust particles were horizontally segmented in the plasma depending on their sizes. The lager ones were distributed outside of the smaller ones. This behaviors was explained by balance of the forces on the dust particles derived in the numerical model with the ambipolar diffusion taken into account.