Vertical String Structure of Fine Particles in a Magnetized DC Plasma

Abstract

This chapter explains vertical string structures of fine particles in a weakly ionized argon dc plasma by applying axial magnetic field in vertical direction. The particles are confined in an extremely narrow radial potential produced by a double plasma method, which enables a formation of a chain-like structure of particles in vertical direction. The fine particles constitute a very thin layer extended in horizontal direction and the properties of the crystal formation are actively investigated theoretically and experimentally The chapter reports that the crystal structures consisting of single chain-like string of fine particles, which is extended in either vertical or horizontal direction, are formed in an rf discharge plasma in the absence of the magnetic field. On the other hand, the collective motions, such as the potential driven vortex flow of fine particles, are observed in fine particle clouds in a dc plasma as well as a vortex formation under the weak magnetic field. Several vertical strings are coupled with each other to constitute three dimensionally characteristic and fundamental lattice structures. It is noted that these coupled vertical strings rotate, as a whole, around the axis that is directed along the vertical magnetic field.