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Particle Pairing In Complex Plasmas

Nosenko, V. and Ivlev, Alexei and Kompaneets, R. and Morfill, Gregor E. (2014) Particle Pairing In Complex Plasmas. 17th International Congress on Plasma Physics, 15-19 September 2014, Lisbon, Portugal.

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Abstract

Pairing of particles is a ubiquitous phenomenon in complex plasmas. The latter are suspensions of charged micron-size solid particles in a plasma, often in the (pre)sheath area above the lower electrode in a gas discharge [1]. Particle pairing was observed in various settings from isolated pairs and larger strings to pairs in 2D crystals and particle bilayers. An important role in the formation of particle pairs belongs to the plasma wakes that appear behind charged particles in the flow of ions. Fundamental questions are what determines the spatial extent of pairs and their stability. These questions recently received attention, but to the best of our knowledge no systematic study was done. In this work, we systematically study the dependence of particle pair size on experimental parameters. We used an experimental setup based on a modified Gaseous Electronics Conference (GEC) radio-frequency (rf) reference cell [2]. Plasma was sustained by a capacitively coupled rf discharge in argon at the pressure of 2 Pa. Melamine-formaldehyde (MF) microspheres with a diameter of 9.19±0.09 μm were suspended in the (pre)sheath area above the lower rf electrode. The particle suspension was imaged from the top and side with two video cameras. A specially designed "pair state" of complex plasma was prepared where particles formed multiple pairs that were vertically oriented, had a well-defined size, and levitated at the same height but were weakly coupled with each other and did not form any regular structure. As the discharge voltage was decreased, the pairs shifted downward and extended vertically. The vertical size of pairs was measured as a function of experimental parameters. We offer an interpretation of our observations based on a recent theory [3] that takes plasma non-uniformity into account. [1] A. Ivlev, H. Löwen, G. Morfill, C. P. Royall, Complex Plasmas and Colloidal Dispersions: Particle-resolved Studies of Classical Liquids and Solids, Series in Soft Condensed Matter Vol. 5 (World Scientific, Singapore, 2012). [2] V. Nosenko, A. V. Ivlev, and G. E. Morfill, Phys. Rev. E 87, 043115 (2013). [3] R. Kompaneets, A. V. Ivlev, V. Nosenko, and G. E. Morfill, Phys. Rev. E, accepted (2014).

Item URL in elib:https://elib.dlr.de/95361/
Document Type:Conference or Workshop Item (Speech)
Title:Particle Pairing In Complex Plasmas
Authors:
AuthorsInstitution or Email of AuthorsAuthors ORCID iD
Nosenko, V.v.nosenko (at) dlr.deUNSPECIFIED
Ivlev, AlexeiMax-Planck-Institut für extraterrestrische Physik, Giessenbachstrasse, 85748 Garching, GermanyUNSPECIFIED
Kompaneets, R.Max-Planck-Institut für extraterrestrische Physik, Giessenbachstrasse, 85748 Garching, GermanyUNSPECIFIED
Morfill, Gregor E.Max-Planck-Institut für extraterrestrische Physik, Giessenbachstrasse, 85748 Garching, GermanyUNSPECIFIED
Date:2014
Refereed publication:Yes
Open Access:No
Gold Open Access:No
In SCOPUS:No
In ISI Web of Science:No
Status:Published
Keywords:complex plasmas, particle pairing
Event Title:17th International Congress on Plasma Physics
Event Location:Lisbon, Portugal
Event Type:international Conference
Event Dates:15-19 September 2014
HGF - Research field:Aeronautics, Space and Transport
HGF - Program:Space
HGF - Program Themes:Research under Space Conditions
DLR - Research area:Raumfahrt
DLR - Program:R FR - Forschung unter Weltraumbedingungen
DLR - Research theme (Project):R - Komplexe Plasmen / Laboratory research
Location: Oberpfaffenhofen
Institutes and Institutions:Research Group Complex Plasma
Deposited By: Nosenko, Volodymyr
Deposited On:23 Feb 2015 16:20
Last Modified:23 Feb 2015 16:20

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