General features and master equations for structurization in complex dusty plasmas
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TOMS, MOLECULES, OPTICS
General Features and Master Equations for Structurization in Complex Dusty Plasmas1 V. N. Tsytovicha and G. E. Morfillb a
General Physics Institute, Russian Academy of Science, Moscow, 119991 Russia Max Planck Institute for Extraterrestrial Physics G85740, Garching, Germany email: [email protected]; [email protected]
b
Received February 24, 2011
Abstract—Dust structurization is considered to be typical for complex plasmas. Homogeneous dusty plasmas are shown to be universally unstable. The dusty plasma structurization instability is similar to the gravitational instability and can results in creation of different compact dust structures. A general approach for investiga tion of the nonlinear stage of structurization in dusty plasmas is proposed and master equations for the description of selforganized structures are formulated in the general form that can be used for any nonlinear model of dust screening. New effects due to the scattering of ions on the nonlinearly screened grains are cal culated: nonlinear ion dust drag force and nonlinear ion diffusion. The physics of confinement of dust and plasma components in the equilibria of compact dust structures is presented and is supported by numerical calculations of master equations. The necessary conditions for the existence of equilibrium structures are found for an arbitrary nonlinearity in dust screening. Features of compact dust structures observed in recent experiments agree with the numerically calculated ones. Some proposals for future experiments in spherical chamber are given. DOI: 10.1134/S1063776112010074 1
1. INTRODUCTION Complexdusty plasmas have been investigated intensively for about 15 years (see reviews [1–7]). The term “complex plasmas” is used in the case where dust grains have large charges and interact strongly. This last effect is of special interest for plasma crystals dis covered in 1964 [8–10], for physics of dust clouds lev itating above etching samples in the plasma etching processes [11], and for dust in fusion devices [12–14]. We here consider the systems containing many grains with large charges (the exact meaning of the term “large dust charge” is given somewhat later). For large dust charges, a new physics related to plasma fluxes on dust grains is important [5]. We briefly explain the main new features in complexdusty plas mas in the case where the dust charges are large (in current experiments, the dust charge in the units of electron charge, Zd, reaches the value 104–105 or even larger). The results obtained previously, for example, in the approaches in [4, 15], using investigations of a single dust grain in plasmas, often cannot be trans ferred to a collection of many dust grains with large charges. The dust charges in plasmas are usually cre ated by plasma fluxes, which increase with an increase in the grain charge. Stationary grain charges should be supported by the presence of continuous electron and ion fluxes with electron–ion recombination inside or on the surface of the grains. In stationary
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