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The Klimontovich description of complex plasma systems: Low frequency electrostatic modes, spectral densities of fluctuations and collision integrals
KTH, School of Electrical Engineering (EES), Space and Plasma Physics. (Complex plasmas)ORCID iD: 0000-0001-9632-8104
2012 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Plasmas seeded with solid particulates of nanometer to micron sizes (complex plasma systems) are a ubiquitous feature of intergalactic, interstellar and planetary environments but also of plasma processing applications or even fusion devices.

Their novel aspects compared with ideal multi-component plasmas stem from (i) the large number of elementary charges residing on the grain surface, (ii) the variability of the charge over mass ratio of the dust component, (iii) the inherent openness and dissipative nature of such systems.

 

Their statistical description presents a major challenge; On one hand by treating dust grains as point particles new phase space variables must be introduced augmenting the classical Hamiltonian phase space, while the microphysics of interaction between the plasma and the grains will introduce additional coupling between the kinetic equations of each species, apart from the usual fine-grained electromagnetic field coupling. On the other hand complex plasma systems do not always exist in a gaseous state but can also condensate, i.e. form liquid, solid or crystalline states.

 

In this thesis we study gaseous partially ionized complex plasma systems from the perspective of the Klimontovich technique of second quantization in phase space. Initially, in regimes typical of dust dynamics. Starting from the Klimontovich equations for the exact phase space densities, theory deliverables such as the permittivity, the spectral densities of fluctuations and the collision integrals are implemented either for concrete predictions related to low frequency electrostatic waves or for diagnostic purposes related to the enhancement of the ion density and electrostatic potential fluctuation spectra due to the presence of dust grains. Particular emphasis is put to the comparison of the self-consistent kinetic model with multi-component kinetic models (treating dust as an additional massive charged species) as well as to the importance of the nature of the plasma particle source. Finally, a new kinetic model of complex plasmas (for both constant and fluctuating sources) is formulated. It is valid in regimes typical of ion dynamics, where plasma discreteness can no longer be neglected, and, in contrast to earlier models, does not require relatively large dust densities to be valid.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2012. , xii, 164 p.
Series
Trita-EE, ISSN 1653-5146 ; 2012:008
Keyword [en]
complex plasmas, dusty plasmas, Klimontovich equations, kinetic theory, dust acoustic waves, collision integrals
National Category
Fusion, Plasma and Space Physics
Identifiers
URN: urn:nbn:se:kth:diva-91506ISBN: 978-91-7501-284-1 (print)OAI: oai:DiVA.org:kth-91506DiVA: diva2:510526
Public defence
2012-03-23, F3, Lindstedsvägen 26, KTH, Stockholm, 13:15 (English)
Opponent
Supervisors
Note
QC 20120316Available from: 2012-03-16 Created: 2012-03-16 Last updated: 2012-03-16Bibliographically approved
List of papers
1. Regimes for experimental tests of kinetic effects in dust acoustic waves
Open this publication in new window or tab >>Regimes for experimental tests of kinetic effects in dust acoustic waves
2010 (English)In: Physics of Plasmas, ISSN 1070-664X, E-ISSN 1089-7674, Vol. 17, no 10, 103707- p.Article in journal (Refereed) Published
Abstract [en]

The low frequency responses of a kinetic model of dusty plasma, taking into account the absorption of the plasma particles on the dust particles and fluctuations of dust charge, are evaluated numerically in order to identify realistic experimental parameter regimes where charging effects are dominant. A range of parameters in terms of dust number density and size as well as plasma densities, where significant differences with the multicomponent approach can be found, is proposed. General expressions for the imaginary parts of the low frequency responses are derived and numerical results for the damping rate in the corresponding ranges are provided to ensure that observations of dust-acoustic waves in those conditions are plausible.

Keyword
low-frequency responses, current glow-discharge, collision integrals, plasmas, instabilities, pk-4
National Category
Fusion, Plasma and Space Physics
Identifiers
urn:nbn:se:kth:diva-27967 (URN)10.1063/1.3491417 (DOI)000283772200086 ()2-s2.0-78149234966 (Scopus ID)
Note

QC 20110103

Available from: 2011-01-03 Created: 2011-01-03 Last updated: 2017-12-11Bibliographically approved
2. Kinetic models of partially ionized complex plasmas in the low frequency regime
Open this publication in new window or tab >>Kinetic models of partially ionized complex plasmas in the low frequency regime
2011 (English)In: Physics of Plasmas, ISSN 1070-664X, E-ISSN 1089-7674, Vol. 18, no 7, 073705- p.Article in journal (Refereed) Published
Abstract [en]

The results from three kinetic models of complex plasmas taking into account collisions with neutrals are compared in the low-frequency regime: The "full" model which considers the absorption of plasma fluxes on dust particles and dust charge fluctuations, the "multi-component" model where both these effects are neglected, and the "standard" model which takes into account the dust charge perturbations but not the absorption of fluxes. We derive and numerically evaluate expressions of the low frequency responses of these models, also taking into account the modification of the capture cross-sections due to the effect of neutrals. The role of plasma sources and collisions with neutrals is assessed by computing the plasma permittivities and static permittivities for all the three models.

National Category
Physical Sciences
Identifiers
urn:nbn:se:kth:diva-38966 (URN)10.1063/1.3615030 (DOI)000293474500057 ()2-s2.0-79961158902 (Scopus ID)
Funder
Swedish Research Council
Note
QC 20110905Available from: 2011-09-05 Created: 2011-09-05 Last updated: 2017-12-08Bibliographically approved
3. Low-frequency electrostatic modes in partially ionized complex plasmas: a kinetic approach
Open this publication in new window or tab >>Low-frequency electrostatic modes in partially ionized complex plasmas: a kinetic approach
2012 (English)In: New Journal of Physics, ISSN 1367-2630, E-ISSN 1367-2630, Vol. 14, 013002- p.Article in journal (Refereed) Published
Abstract [en]

A kinetic model of partially ionized complex plasmas is employed for the numerical analysis of low-frequency longitudinal modes for typical laboratory plasmas. The approach self-consistently includes the effects of plasma particle absorption on dust, collisions with neutrals and electron impact ionization. In addition to the typical dust acoustic mode, the results reveal the existence of a novel long-wavelength mode, attributed to the interplay between the mechanisms of plasma production and loss. The main properties of mode dispersions are investigated through their dependence on plasma and dust parameters.

National Category
Physical Sciences
Identifiers
urn:nbn:se:kth:diva-91270 (URN)10.1088/1367-2630/14/1/013002 (DOI)000300411700002 ()2-s2.0-84856423990 (Scopus ID)
Note
QC 20120312Available from: 2012-03-12 Created: 2012-03-12 Last updated: 2017-12-07Bibliographically approved
4. Grain charging in an intermediately collisional plasma
Open this publication in new window or tab >>Grain charging in an intermediately collisional plasma
Show others...
2012 (English)In: Europhysics letters, ISSN 0295-5075, E-ISSN 1286-4854, Vol. 97, no 3, 35001- p.Article in journal (Refereed) Published
Abstract [en]

The charges of mu m-size particles in the quasineutral bulk plasma of a dc discharge are determined experimentally in a pressure range between 100 and 500 Pa, spanning the transition between the weakly collisional and highly collisional (hydrodynamic) regimes, where the ion mean free path drops below the plasma screening length. The charge is determined using the force balance condition from the measured particle drift velocities in stable particle flows. A simple interpolation formula for the ion flux to the grain in the transitional regime is shown to fit quite well the experimental results.

National Category
Physical Sciences
Identifiers
urn:nbn:se:kth:diva-91254 (URN)10.1209/0295-5075/97/35001 (DOI)000300400000022 ()2-s2.0-84857094703 (Scopus ID)
Note
QC 20120312Available from: 2012-03-12 Created: 2012-03-12 Last updated: 2017-12-07Bibliographically approved
5. Spectra of ion density and potential fluctuations in weakly ionized plasmas in the presence of dust grains
Open this publication in new window or tab >>Spectra of ion density and potential fluctuations in weakly ionized plasmas in the presence of dust grains
2012 (English)In: Physical Review E. Statistical, Nonlinear, and Soft Matter Physics, ISSN 1539-3755, E-ISSN 1550-2376, Vol. 85, no 2, 026408-1-026408-9 p.Article in journal (Refereed) Published
Abstract [en]

The spectral densities of ion density and electrostatic potential fluctuations are derived in the framework of a self-consistent kinetic model of partially ionized dusty plasmas in the low-frequency regime. Neutral gas density can be responsible for significant modifications of the fluctuation level, hence the inclusion of the effect of neutrals is essential for a more realistic comparison with experiments, especially if spectral measurements are intended for dust diagnostic purposes. Comparison with the multicomponent model, attractive due to its simplicity as compared to the self-consistent one, is carried out to establish its limits of validity. Numerical calculations are performed for parameters typical of low-temperature plasma discharges. A criterion is derived for the omission of plasma discreteness in the low-frequency regime.

Keyword
spectral densities, complex plasmas, partially ionized plasmas, fluctuation theory, dust diagnostic
National Category
Fusion, Plasma and Space Physics
Identifiers
urn:nbn:se:kth:diva-91510 (URN)10.1103/PhysRevE.85.026408 (DOI)000300672700006 ()2-s2.0-84857735333 (Scopus ID)
Funder
Swedish Research Council
Note
QC 20120316Available from: 2012-03-16 Created: 2012-03-16 Last updated: 2017-12-07Bibliographically approved
6. Effects of dust particles in plasma kinetics; ion dynamics time scales
Open this publication in new window or tab >>Effects of dust particles in plasma kinetics; ion dynamics time scales
2012 (English)In: Physics of Plasmas, ISSN 1070-664X, E-ISSN 1089-7674, Vol. 19, no 7, 073701- p.Article in journal (Refereed) Published
Abstract [en]

The self-consistent kinetic theory of dusty plasmas [V. N. Tsytovich and U. de Angelis, Phys. Plasmas 6, 1093 (1999)] is extended to frequency regimes relevant for ion dynamics, accounting for both constant and fluctuating plasma sources. In contrast to earlier models, binary plasma collisions are no longer neglected with respect to collisions with dust; hence, the model developed here is also valid for low dust densities. Expressions are found for the system's permittivity, the ion collision integral, and the spectral densities of ion density fluctuations. The structure of the ion kinetic equation is analyzed, and applications of the model for both astrophysical and laboratory environments are discussed.

Keyword
complex plasmas, dusty plasmas, kinetic models, Klimontovich equation, plasma discreteness, collision integrals, Lennard-Balescu, spectral densities, permittivity
National Category
Fusion, Plasma and Space Physics
Identifiers
urn:nbn:se:kth:diva-91513 (URN)10.1063/1.4728084 (DOI)000307422800128 ()2-s2.0-84866952042 (Scopus ID)
Funder
Swedish Research Council
Note

QC 20120928

Available from: 2012-03-16 Created: 2012-03-16 Last updated: 2017-12-07Bibliographically approved

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