Convective Dust Clouds Driven by Thermal Creep in a Complex Plasma

Abstract

Steady-state clouds of microparticles were observed, levitating in a low-frequency glow discharge generated in an elongated vertical glass tube. A heated ring was attached to the tube wall outside, so that the particles, exhibiting a global convective motion, were confined vertically in the region above the location of the heater. It is shown that the particle vortices were induced by the convection of neutral gas, and the mechanism responsible for the gas convection was the thermal creep along the inhomogeneously heated tube walls. The phenomenon of thermal creep, which commonly occurs in rarefied gases under the presence of thermal gradients, should generally play a substantial role in experiments with complex plasmas.

Computer tomography of large dust clouds in complex plasmas

“…2(b) is often seen in experiments on spatially extended dust clouds and may possibly derive from intrinsic plasma forces 13 or unwanted thermal gradients due to the tempered electrodes. 25 Performing both the extinction measurement and the laser slice technique simultaneously, dynamical phenomena such as dust density waves can be investigated with respect to their global and local properties. 27…”

Phase Transitions in Two-Dimensional Complex Plasmas

“…Therefore it is proportional to the thermal conductivity of the gas κ T , the temperature gradient and the squared particle radius: F th ∝ a 2 κ T ∇T N . Thermophoresis can be used to levitate particles in a plasma chamber against gravity into regions in the bulk plasma, providing similar conditions as experiments in microgravity, and it can lead to other interesting phenomena such as convection, circulations and formation of structures [107,108,109,110].…”

Observation of dust torus with poloidal rotation in direct current glow discharge plasma

“…Vaulina et al 4,[16][17][18] and Samarian et al 19 attributed that dust charge gradient in an inhomogeneous plasma in the presence of a non-electrostatic force orthogonal to it causes an instability which leads to the formation of the dust vortices. Mittic et al 20 reported the formation of dust vortices due to thermal creep flow (TCF) in a low frequency discharge produced in an inhomogeneously heated vertical glass tube at low pressures. Later, Flanagan et al 21 designed an experiment to isolate TCF from other temperature gradient driven effects and verified its role on vorticity formation at low pressures.…”