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Title: Theory of 'virtual' dust voids: the stability of void structures

Abstract

Experiments demonstrate a variety of dust void structures such as stable or unstable voids, global 'heatbeat' modes of oscillations of voids, dust voids in the center of the chamber or near its walls. Theory shows that a dust void generally results from the balance of the electrostatic and the plasma (such as the ion drag) forces acting on a dust particle. Here, the stability theory of a 'virtual' void is developed and its behavior is modeled. It is shown that sequences of stable and unstable void sizes can exist. The dynamics of dust in a plasma follows these stability characteristics leading to various stable and/or unstable dust void structures.

Authors:
 [1];  [2];  [3]
  1. School of Physics, University of Sydney, New South Wales 2006 (Australia)
  2. General Physics Institute, Russian Academy of Science, Vavilova St. 38, 117942 Moscow (Russian Federation)
  3. Max-Planck-Institut fuer extraterrrestrische Physik, D-85740 Garching (Germany)
Publication Date:
OSTI Identifier:
20726754
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Conference Proceedings; Journal Volume: 799; Journal Issue: 1; Conference: 4. international conference on the physics of dusty plasmas, Orleans (France), 13-17 Jun 2005; Other Information: DOI: 10.1063/1.2134606; (c) 2005 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; DUSTS; IONS; OSCILLATIONS; PARTICLES; PLASMA; SOLIDS; STABILITY; VOIDS

Citation Formats

Vladimirov, S.V., Tsytovich, V.N., and Morfill, G.E. Theory of 'virtual' dust voids: the stability of void structures. United States: N. p., 2005. Web. doi:10.1063/1.2134606.
Vladimirov, S.V., Tsytovich, V.N., & Morfill, G.E. Theory of 'virtual' dust voids: the stability of void structures. United States. doi:10.1063/1.2134606.
Vladimirov, S.V., Tsytovich, V.N., and Morfill, G.E. Mon . "Theory of 'virtual' dust voids: the stability of void structures". United States. doi:10.1063/1.2134606.
@article{osti_20726754,
title = {Theory of 'virtual' dust voids: the stability of void structures},
author = {Vladimirov, S.V. and Tsytovich, V.N. and Morfill, G.E.},
abstractNote = {Experiments demonstrate a variety of dust void structures such as stable or unstable voids, global 'heatbeat' modes of oscillations of voids, dust voids in the center of the chamber or near its walls. Theory shows that a dust void generally results from the balance of the electrostatic and the plasma (such as the ion drag) forces acting on a dust particle. Here, the stability theory of a 'virtual' void is developed and its behavior is modeled. It is shown that sequences of stable and unstable void sizes can exist. The dynamics of dust in a plasma follows these stability characteristics leading to various stable and/or unstable dust void structures.},
doi = {10.1063/1.2134606},
journal = {AIP Conference Proceedings},
number = 1,
volume = 799,
place = {United States},
year = {Mon Oct 31 00:00:00 EST 2005},
month = {Mon Oct 31 00:00:00 EST 2005}
}
  • A dust void is a dust-free region inside the dust cloud that often develops for conditions relevant to plasma processing discharges and complex plasma experiments. A distinctive feature of the void is a sharp boundary between the dust and dust-free regions; this is manifested especially clear when dissipation in the plasma is small and discontinuity of the dust number density appear. Here, the structure of the dust void boundary and the distribution of the dust and plasma parameters in the dust structure bordering the void is analyzed taking into account effects of dissipation due to the ion diffusion on plasmamore » neutrals. The sharp boundary between the dust and void regions exists also in the presence of the ion diffusion; however, only derivatives of the dust density, dust charge, electron density and electric field are discontinuous at the void boundaries, while the functions themselves as well as derivatives of the ion drift velocity and the ion density are continuous. Numerical calculations demonstrate various sorts of diffusive dust void structures; the possibility of singularities in the balance equations caused by the diffusion process inside the dust structures is investigated. These singularities can be responsible for a new type of shocklike structures. Other structures are typically self-organized to eliminate the singularities. Numerical computations in this case demonstrate a set of thin dust layers separated by high density thin dust clouds similar to the multiple-layer dust structures observed in the laboratory and in the upper ionosphere. The possibility for existence of a few equilibrium positions of the void boundary is discussed.« less
  • The structure of the dust void boundary and the distribution of the dust and plasma parameters in the dust structure bordering the void is analyzed taking into account effects of dissipation due to the ion diffusion on plasma neutrals. Numerical calculations demonstrate various sorts of diffusive dust void structures; the possibility of singularities in the balance equations caused by the diffusion process inside the dust structures is investigated. These singularities can be responsible for a new type of shock-like structures.
  • The steady structures of dust voids in electronegative plasmas for different ionization rates are investigated using fluid theory. The effects of the concentration of negative ions in plasmas on the distributions of the electric field and the potential in the region of voids as well as Mach number are analyzed numerically. The results show that when the ionization rate is lower, the steady structures do not appear. With an increase of the ionization rate, the steady structures can be formed. The latter are affected by the concentration of the negative ions. With increasing negative ions, the potential decays, and themore » Mach number as well as the electric field increases. It is also found that increasing both the concentration of the negative ions and the ionization rate can gives rise to contraction of the steady void structures.« less
  • Dust voids are frequently observed as dust-free regions in a dusty plasma. Experiments demonstrate a variety of dust void structures such as stable or unstable voids, global 'heatbeat' modes of oscillations of voids, dust voids in the center of the chamber or near its walls. Theory shows that a dust void generally results from the balance of the electrostatic and the plasma (such as the ion drag) forces acting on a dust particle. Here, the stability theory of a void is developed and the void behavior is modeled. It is shown that sequences of stable and unstable void sizes canmore » exist. The dynamics of dust in a plasma follows these stability characteristics leading to various stable and/or unstable dust void structures.« less
  • A time-dependent, self-consistent nonlinear model with the convective term for the void formation in dusty plasmas is given. Furthermore, the cylindrical configuration is applied instead of the Cartesian system, considering the device geometry in experiments. The nonlinear evolution of the dust void is then investigated numerically. It is shown that, similar to the slab model, the ion drag plays a crucial role in the evolution of the void. However, the effect of the convective term slows down the void formation process and the void size obtained in the cylindrical coordinate is larger than that obtained in the Cartesian coordinates.