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Singh S, Bandyopadhyay P, Kumar K, Sen A. Square Lattice Formation in a Monodisperse Complex Plasma. PHYSICAL REVIEW LETTERS 2022; 129:115003. [PMID: 36154432 DOI: 10.1103/physrevlett.129.115003] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/02/2022] [Revised: 06/01/2022] [Accepted: 07/25/2022] [Indexed: 06/16/2023]
Abstract
We present the first observations of a square lattice formation in a monodisperse complex plasma system, a configurational transition phenomenon that has long been an experimental challenge in the field. The experiments are conducted in a tabletop L-shaped dusty plasma experimental device in a dc glow discharge Argon plasma environment. By a careful control of the vertical potential confining the charged particles as well as the strength of the ion wake charge interactions with the dust particles, we are able to steer the system toward a crystalline phase that exhibits a square lattice configuration. The transition occurs when the vertical confinement strength is slightly reduced below a critical value leading to a buckling of the monodisperse hexagonal 2D dust crystal to form a narrowly separated bilayer state (a quasi-2D state). Some theoretical insights into the transition process are provided through molecular dynamics simulations carried out for the parameters relevant to our experiment.
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Affiliation(s)
- Swarnima Singh
- Institute for Plasma Research, A CI of Homi Bhabha National Institute, Bhat, Gandhinagar-382428, India
| | - P Bandyopadhyay
- Institute for Plasma Research, A CI of Homi Bhabha National Institute, Bhat, Gandhinagar-382428, India
| | - Krishan Kumar
- Institute for Plasma Research, A CI of Homi Bhabha National Institute, Bhat, Gandhinagar-382428, India
| | - A Sen
- Institute for Plasma Research, A CI of Homi Bhabha National Institute, Bhat, Gandhinagar-382428, India
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2
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Self-sustained non-equilibrium co-existence of fluid and solid states in a strongly coupled complex plasma system. Sci Rep 2022; 12:13882. [PMID: 35974028 PMCID: PMC9381532 DOI: 10.1038/s41598-022-17939-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2022] [Accepted: 08/03/2022] [Indexed: 12/03/2022] Open
Abstract
A complex (dusty) plasma system is well known as a paradigmatic model for studying the kinetics of solid-liquid phase transitions in inactive condensed matter. At the same time, under certain conditions a complex plasma system can also display characteristics of an active medium with the micron-sized particles converting energy of the ambient environment into motility and thereby becoming active. We present a detailed analysis of the experimental complex plasmas system that shows evidence of a non-equilibrium stationary coexistence between a cold crystalline and a hot fluid state in the structure due to the conversion of plasma energy into the motion energy of microparticles in the central region of the system. The plasma mediated non-reciprocal interaction between the dust particles is the underlying mechanism for the enormous heating of the central subsystem, and it acts as a micro-scale energy source that keeps the central subsystem in the molten state. Accurate multiscale simulations of the system based on combined molecular dynamics and particle-in-cell approaches show that strong structural nonuniformity of the system under the action of electostatic trap makes development of instabilities a local process. We present both experimental tests conducted with a complex plasmas system in a DC glow discharge plasma and a detailed theoretical analysis.
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3
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Couëdel L, Nosenko V. Stability of two-dimensional complex plasma monolayers in asymmetric capacitively coupled radio-frequency discharges. Phys Rev E 2022; 105:015210. [PMID: 35193236 DOI: 10.1103/physreve.105.015210] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2021] [Accepted: 01/11/2022] [Indexed: 06/14/2023]
Abstract
In this article, the stability of a complex plasma monolayer levitating in the sheath of the powered electrode of an asymmetric capacitively coupled radio-frequency argon discharge is studied. Compared to earlier studies, a better integration of the experimental results and theory is achieved by operating with actual experimental control parameters such as the gas pressure and the discharge power. It is shown that for a given microparticle monolayer at a fixed discharge power there exist two threshold pressures: (i) above a specific pressure p_{cryst}, the monolayer always crystallizes; (ii) below a specific pressure p_{MCI}, the crystalline monolayer undergoes the mode-coupling instability and the two-dimensional complex plasma crystal melts. In between p_{MCI} and p_{cryst}, the microparticle monolayer can be either in the fluid phase or the crystal phase: when increasing the pressure from below p_{MCI}, the monolayer remains in the fluid phase until it reaches p_{cryst} at which it recrystallizes; when decreasing the pressure from above p_{cryst}, the monolayer remains in the crystalline phase until it reaches p_{MCI} at which the mode-coupling instability is triggered and the crystal melts. A simple self-consistent sheath model is used to calculate the rf sheath profile, the microparticle charges, and the microparticle resonance frequency as a function of power and background argon pressure. Combined with calculation of the lattice modes the main trends of p_{MCI} as a function of power and background argon pressure are recovered. The threshold of the mode-coupling instability in the crystalline phase is dominated by the crossing of the longitudinal in-plane lattice mode and the out-of plane lattice mode induced by the change of the sheath profile. Ion wakes are shown to have a significant effect too.
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Affiliation(s)
- L Couëdel
- Physics and Engineering Physics Department, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5E2, Canada
- CNRS, Aix-Marseille Université, Laboratoire PIIM UMR 7345, 13397 Marseille cedex 20, France
| | - V Nosenko
- Institut für Materialphysik im Weltraum, Deutsches Zentrum für Luft- und Raumfahrt (DLR), D-82234 Weßling, Germany
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4
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Alignments of a Microparticle Pair in a Glow Discharge. Molecules 2021; 26:molecules26247535. [PMID: 34946617 PMCID: PMC8707345 DOI: 10.3390/molecules26247535] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2021] [Revised: 12/08/2021] [Accepted: 12/10/2021] [Indexed: 11/16/2022] Open
Abstract
Stability of a vertically aligned microparticle pair in a stratified glow DC discharge is experimentally investigated. Using laser perturbations, it is shown that, for the same discharge parameters, a pair of microparticles can be suspended in two stable configurations: vertical and horizontal. The interparticle interaction and the electric field of the stratum in the region of particle levitation are quantitatively investigated for the first time. The decharging effect of the lower (downstream) particle by the ion flow wake is also observed for the first time in a glow discharge. The obtained experimental data made it possible to check the analytical criteria for the configurational stability of the system.
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5
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Ding Z, Matthews LS, Hyde TW. A machine learning based Bayesian optimization solution to non-linear responses in dusty plasmas. MACHINE LEARNING: SCIENCE AND TECHNOLOGY 2021. [DOI: 10.1088/2632-2153/abe7b7] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Abstract
Nonlinear frequency response analysis is a widely used method for determining system dynamics in the presence of nonlinearities. In dusty plasmas, the plasma–grain interaction (e.g. grain charging fluctuations) can be characterized by a single-particle non-linear response analysis, while grain–grain non-linear interactions can be determined by a multi-particle non-linear response analysis. Here a machine learning-based method to determine the equation of motion in the non-linear response analysis for dust particles in plasmas is presented. Searching the parameter space in a Bayesian manner allows an efficient optimization of the parameters needed to match simulated non-linear response curves to experimentally measured non-linear response curves.
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6
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Zampetaki AV, Huang H, Du CR, Löwen H, Ivlev AV. Buckling of two-dimensional plasma crystals with nonreciprocal interactions. Phys Rev E 2020; 102:043204. [PMID: 33212619 DOI: 10.1103/physreve.102.043204] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2020] [Accepted: 09/15/2020] [Indexed: 11/07/2022]
Abstract
Laboratory realizations of two-dimensional (2D) plasma crystals typically involve monodisperse microparticles confined into horizontal monolayers in radio-frequency (rf) plasma sheaths. This gives rise to the so-called plasma wakes beneath the microparticles. The presence of wakes renders the interactions in such systems nonreciprocal, a fact that can lead to a quite different behavior from the one expected for their reciprocal counterparts. Here we examine the buckling of a hexagonal 2D plasma crystal, occurring as the confinement strength is decreased, taking explicitly into account the nonreciprocity of the system via a well-established point-wake model. We observe that for a finite wake charge, the monolayer hexagonal crystal undergoes a transition first to a bilayer hexagonal structure, unrealizable in harmonically confined reciprocal Yukawa systems, and subsequently to a bilayer square structure. Our theoretical results are confirmed by molecular dynamics simulations for experimentally relevant parameters, indicating the potential of their observation in state-of-the-art experiments with 2D complex plasmas.
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Affiliation(s)
- A V Zampetaki
- Max-Planck-Institut für Extraterrestrische Physik, 85741 Garching, Germany.,Institut für Theoretische Physik II, Weiche Materie, Heinrich-Heine-Universität, 40225 Düsseldorf, Germany
| | - H Huang
- College of Science, Donghua University, 201620 Shanghai, People's Republic of China
| | - C-R Du
- College of Science, Donghua University, 201620 Shanghai, People's Republic of China
| | - H Löwen
- Institut für Theoretische Physik II, Weiche Materie, Heinrich-Heine-Universität, 40225 Düsseldorf, Germany
| | - A V Ivlev
- Max-Planck-Institut für Extraterrestrische Physik, 85741 Garching, Germany
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7
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Ashrafi KS, Yousefi R, Chen M, Matthews LS, Hyde TW. Dust as probes: Determining confinement and interaction forces. Phys Rev E 2020; 102:043210. [PMID: 33212567 DOI: 10.1103/physreve.102.043210] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2020] [Accepted: 09/21/2020] [Indexed: 11/07/2022]
Abstract
Complex plasmas are interesting systems as the charged dust can self-assemble into different types of ordered structures. To understand the mechanisms which govern the transitions from one type of structure to another, it is necessary to know both the dust charge and the confining electric fields within the environment, parameters which are difficult to measure independently. As dust is usually confined in a plasma sheath where the ions stream from the bulk plasma to the negative lower electrode, the problem is further complicated by the ion wake field, which develops downstream of the dust grains in a flowing plasma. The differences in local ion density caused by the wake field change the equilibrium dust charge and shielding distance of the dust grains, and thus affect the interaction between grains. Here we use a molecular dynamics simulation of ion flow past dust grains to investigate the interaction between the dust particles and ions. We consider a long vertical chain of particles confined within a glass box placed on the lower electrode of a Gaseous Electronics Conference rf reference cell. We apply the model iteratively to self-consistently determine the dust charge, electric field, and ion density along the length of the chain as well as the ion flow speed. Simulation results indicate that the ion flow speed within the box is subsonic.
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Affiliation(s)
| | - Razieh Yousefi
- The University of Texas Medical Branch, Galveston, Texas 77555, USA
| | - Mudi Chen
- CASPER, Baylor University, Waco, Texas 76798-7316, USA
| | | | - Truell W Hyde
- CASPER, Baylor University, Waco, Texas 76798-7316, USA
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8
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Maity S, Deshwal P, Yadav M, Das A. Dynamical states in two-dimensional charged dust particle clusters in plasma medium. Phys Rev E 2020; 102:023213. [PMID: 32942517 DOI: 10.1103/physreve.102.023213] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2020] [Accepted: 08/12/2020] [Indexed: 11/07/2022]
Abstract
The formation of dynamical states for a collection of dust particles in two dimensions is shown using molecular dynamics simulations. The charged dust particles interact with each other with a Yukawa pair potential mimicking the screening due to plasma. An external radial confining force has also been applied to the dust particles to keep them radially confined. When the particle number is low (say, a few), they get arranged on the radial locations corresponding to multiple rings or shells. For specific numbers, such an arrangement of particles is stationary. However, for several cases, the cluster of dust particles relaxes to a state for which the dust particles on rings display intershell rotation. For a larger number of dust particles (a few hundred, for instance), an equilibrium state with a coherent rigid body displaying angular oscillation of the entire cluster is observed. A detailed characterization of the formation of these states in terms of particle number, coupling parameter, etc., is provided.
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Affiliation(s)
- Srimanta Maity
- Physics Department, IIT Delhi, Hauz Khas, New Delhi 110016, India
| | - Priya Deshwal
- Physics Department, IIT Delhi, Hauz Khas, New Delhi 110016, India
| | - Mamta Yadav
- Physics Department, IIT Delhi, Hauz Khas, New Delhi 110016, India
| | - Amita Das
- Physics Department, IIT Delhi, Hauz Khas, New Delhi 110016, India
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9
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Sundar S, Moldabekov ZA. Plasma-grain interaction mediated by streaming non-Maxwellian ions. Phys Rev E 2019; 99:063202. [PMID: 31330743 DOI: 10.1103/physreve.99.063202] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2019] [Indexed: 11/07/2022]
Abstract
A comprehensive parametric study of plasma-grain interaction for non-Maxwellian streaming ions in steady-state employing particle-in-cell simulations is delineated. Instead of considering the intergrain interaction potential to be the linear sum of isolated grain potentials, we incorporate the numerical advancement developed fully for grain shielding by including nonlinear contributions from the plasma and shadowing effect. The forces acting on grains versus intergrain distance, streaming velocity of the ions, and impact of trapped ions density (number) are characterized for non-Maxwellian ions in the presence of charge-exchange collisions. It is found that the nonlinear plasma response considerably modifies the plasma-grain interaction. Unlike the stationary plasma case, for two identical grains separated by a distance in the presence of streaming ions, the electrostatic force is neither repulsive for all grain separations nor equivalent to the force due to one isolated grain. Inadequacy of the linear response formalism in dealing with the systems having very large grain charges is also discussed. The smallest intergrain separation for which the role of the shadow effect can be ignored is reported.
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Affiliation(s)
- Sita Sundar
- Department of Aerospace Engineering, Indian Institute of Technology Madras, Chennai-600036, India
| | - Zhandos A Moldabekov
- Institute for Experimental and Theoretical Physics, Al-Farabi Kazakh National University, 71 Al-Farabi Strasse, 050040 Almaty, Kazakhstan.,Institute of Applied Sciences and IT, 40-48 Shashkin Strasse, 050038 Almaty, Kazakhstan
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10
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Wang K, Huang D, Feng Y. Shear modulus of two-dimensional Yukawa or dusty-plasma solids obtained from the viscoelasticity in the liquid state. Phys Rev E 2019; 99:063206. [PMID: 31330584 DOI: 10.1103/physreve.99.063206] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2019] [Indexed: 11/07/2022]
Abstract
Langevin dynamical simulations of two-dimensional (2D) Yukawa liquids are performed to investigate the shear modulus of 2D solid dusty plasmas. Using the known transverse sound speeds, we obtain a theoretical expression of the shear modulus of 2D Yukawa crystals as a function of the screening parameter κ, which can be used as the candidate of their shear modulus. The shear relaxation modulus G(t) of 2D Yukawa liquids is calculated from the shear stress autocorrelation function, consisting of the kinetic, potential, and cross portions. Due to their viscoelasticity, 2D Yukawa liquids exhibit the typical elastic property when the time duration is much less than the Maxwell relaxation time. As a result, the infinite frequency shear modulus G_{∞}, i.e., the shear relaxation modulus G(t) when t=0, of a 2D Yukawa liquid should be related to the shear modulus of the corresponding quenched 2D Yukawa solid (with the same κ value), with all particles suddenly frozen at their locations of the liquid state. It is found that the potential portion of the infinite frequency shear modulus for 2D Yukawa liquids at any temperature well agrees with the shear modulus of 2D Yukawa crystals with the same κ obtained from the transverse sound speeds. Thus, we find that the shear modulus of 2D Yukawa solids can be obtained from the motion of individual particles of the corresponding Yukawa liquids using their viscoelastic property.
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Affiliation(s)
- Kang Wang
- Center for Soft Condensed Matter Physics and Interdisciplinary Research, School of Physical Science and Technology, Soochow University, Suzhou 215006, China
| | - Dong Huang
- Center for Soft Condensed Matter Physics and Interdisciplinary Research, School of Physical Science and Technology, Soochow University, Suzhou 215006, China
| | - Yan Feng
- Center for Soft Condensed Matter Physics and Interdisciplinary Research, School of Physical Science and Technology, Soochow University, Suzhou 215006, China
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11
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Couëdel L, Nosenko V. Tracking and Linking of Microparticle Trajectories During Mode-Coupling Induced Melting in a Two-Dimensional Complex Plasma Crystal. J Imaging 2019; 5:jimaging5030041. [PMID: 34460469 PMCID: PMC8320910 DOI: 10.3390/jimaging5030041] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2019] [Revised: 03/11/2019] [Accepted: 03/12/2019] [Indexed: 11/17/2022] Open
Abstract
In this article, a strategy to track microparticles and link their trajectories adapted to the study of the melting of a quasi two-dimensional complex plasma crystal induced by the mode-coupling instability is presented. Because of the three-dimensional nature of the microparticle motions and the inhomogeneities of the illuminating laser light sheet, the scattered light intensity can change significantly between two frames, making the detection of the microparticles and the linking of their trajectories quite challenging. Thanks to a two-pass noise removal process based on Gaussian blurring of the original frames using two different kernel widths, the signal-to-noise ratio was increased to a level that allowed a better intensity thresholding of different regions of the images and, therefore, the tracking of the poorly illuminated microparticles. Then, by predicting the positions of the microparticles based on their previous positions, long particle trajectories could be reconstructed, allowing accurate measurement of the evolution of the microparticle energies and the evolution of the monolayer properties.
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Affiliation(s)
- Lénaïc Couëdel
- Department of Physics and Engineering Physics, University of Saskatchewan, Saskatoon, SK S7N 5E2, Canada
- CNRS, Aix-Marseille Université, PIIM, UMR 7345, 13397 Marseille CEDEX 20, France
- Correspondence: or
| | - Vladimir Nosenko
- Institut für Materialphysik im Weltraum, Deutsches Zentrum für Luft- und Raumfahrt (DLR), D-82234 Weßling, Germany
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12
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Koss XG, Petrov OF, Statsenko KB, Vasiliev MM. Small systems of laser-driven active Brownian particles: Evolution and dynamic entropy. ACTA ACUST UNITED AC 2018. [DOI: 10.1209/0295-5075/124/45001] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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13
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Couëdel L, Nosenko V, Rubin-Zuzic M, Zhdanov S, Elskens Y, Hall T, Ivlev AV. Full melting of a two-dimensional complex plasma crystal triggered by localized pulsed laser heating. Phys Rev E 2018; 97:043206. [PMID: 29758736 DOI: 10.1103/physreve.97.043206] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2017] [Indexed: 06/08/2023]
Abstract
The full melting of a two-dimensional plasma crystal was induced in a principally stable monolayer by localized laser stimulation. Two distinct behaviors of the crystal after laser stimulation were observed depending on the amount of injected energy: (i) below a well-defined threshold, the laser melted area recrystallized; (ii) above the threshold, it expanded outwards in a similar fashion to mode-coupling instability-induced melting, rapidly destroying the crystalline order of the whole complex plasma monolayer. The reported experimental observations are due to the fluid mode-coupling instability, which can pump energy into the particle monolayer at a rate surpassing the heat transport and damping rates in the energetic localized melted spot, resulting in its further growth. This behavior exhibits remarkable similarities with impulsive spot heating in ordinary reactive matter.
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Affiliation(s)
- L Couëdel
- Department of Physics and Engineering Physics, University of Saskatchewan, Saskatoon, SK S7N 5E2, Canada
- Aix-Marseille Université, CNRS, PIIM, UMR 7345, 13397 Marseille cedex 20, France
- Department of Physics, Auburn University, Auburn, Alabama 36849, USA
| | - V Nosenko
- Institut für Materialphysik im Weltraum, Deutsches Zentrum für Luft und Raumfahrt, D-82234 Weßling, Germany
| | - M Rubin-Zuzic
- Institut für Materialphysik im Weltraum, Deutsches Zentrum für Luft und Raumfahrt, D-82234 Weßling, Germany
| | - S Zhdanov
- Institut für Materialphysik im Weltraum, Deutsches Zentrum für Luft und Raumfahrt, D-82234 Weßling, Germany
| | - Y Elskens
- Aix-Marseille Université, CNRS, PIIM, UMR 7345, 13397 Marseille cedex 20, France
| | - T Hall
- Department of Physics, Auburn University, Auburn, Alabama 36849, USA
| | - A V Ivlev
- Max Planck Institute for Extraterrestrial Physics, D-85741 Garching, Germany
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14
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Nosenko V, Zhdanov SK, Thomas HM, Carmona-Reyes J, Hyde TW. Dynamics of spinning particle pairs in a single-layer complex plasma crystal. Phys Rev E 2018; 96:011201. [PMID: 29347228 DOI: 10.1103/physreve.96.011201] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2017] [Indexed: 11/07/2022]
Abstract
Spontaneous formation of spinning pairs of particles, or torsions, is studied in a single-layer complex plasma crystal by reducing the discharge power at constant neutral gas pressure. At higher gas pressures, torsions spontaneously form below a certain power threshold. Further reduction of the discharge power leads to the formation of multiple torsions. However, at lower gas pressures the torsion formation is preceded by mode-coupling instability (MCI). The crystal dynamics are studied with the help of the fluctuation spectra of crystal particles' in-plane velocities. Surprisingly, the spectra of the crystal with torsions and MCI are rather similar and contain hot spots at similar locations on the (k,ω) plane, despite very different appearances of the respective particle trajectories. The torsion rotation speed is close (slightly below) to the maximum frequency of the in-plane compressional mode. When multiple torsions form, their rotation speeds are distributed in a narrow range slightly below the maximum frequency.
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Affiliation(s)
- V Nosenko
- Institut für Materialphysik im Weltraum, Deutsches Zentrum für Luft- und Raumfahrt, 82234 Weßling, Germany.,Center for Astrophysics, Space Physics, and Engineering Research, Baylor University, Waco, Texas 76798-7310, USA
| | - S K Zhdanov
- Institut für Materialphysik im Weltraum, Deutsches Zentrum für Luft- und Raumfahrt, 82234 Weßling, Germany
| | - H M Thomas
- Institut für Materialphysik im Weltraum, Deutsches Zentrum für Luft- und Raumfahrt, 82234 Weßling, Germany
| | - J Carmona-Reyes
- Center for Astrophysics, Space Physics, and Engineering Research, Baylor University, Waco, Texas 76798-7310, USA
| | - T W Hyde
- Center for Astrophysics, Space Physics, and Engineering Research, Baylor University, Waco, Texas 76798-7310, USA
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15
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Mulsow M, Melzer A. Experimental determination of phase transitions by means of configurational entropies in finite Yukawa balls. Phys Rev E 2018; 96:053202. [PMID: 29347803 DOI: 10.1103/physreve.96.053202] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2017] [Indexed: 11/07/2022]
Abstract
The phase transition of finite Yukawa balls (ordered systems of microspheres in a gaseous plasma environment) with less than 100 particles is studied experimentally by means of configurational entropies. We have developed cylindrical two- and three-particle-correlation functions to measure these entropies for multiple cluster sizes over a wide temperature range. The cluster temperature is finely tuned using a stochastic laser heating setup. It is shown that the correlation functions give a detailed insight into the structural properties of the cluster. The derived configurational entropies give a clear indication of the transition temperature from a solid-like to a fluid-like state. Comparing the transition temperatures of different sized clusters it is found that the transition temperature increases with cluster size in general agreement with theoretical predictions.
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Affiliation(s)
- Matthias Mulsow
- Institut für Physik, Ernst-Moritz-Arndt-Universität Greifswald, 17489 Greifswald, Germany
| | - André Melzer
- Institut für Physik, Ernst-Moritz-Arndt-Universität Greifswald, 17489 Greifswald, Germany
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16
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Meyer JK, Laut I, Zhdanov SK, Nosenko V, Thomas HM. Coupling of Noncrossing Wave Modes in a Two-Dimensional Plasma Crystal. PHYSICAL REVIEW LETTERS 2017; 119:255001. [PMID: 29303297 DOI: 10.1103/physrevlett.119.255001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/03/2017] [Indexed: 06/07/2023]
Abstract
We report an experimental observation of the coupling of the transverse vertical and longitudinal in-plane dust-lattice wave modes in a two-dimensional complex plasma crystal in the absence of mode crossing. A new large-diameter rf plasma chamber was used to suspend the plasma crystal. The observations are confirmed with molecular dynamics simulations. The coupling manifests itself in traces of the transverse vertical mode appearing in the measured longitudinal spectra and vice versa. We calculate the expected ratio of the trace to the principal mode with a theoretical analysis of the modes in a crystal with finite temperature and find good agreement with the experiment and simulations.
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Affiliation(s)
- J K Meyer
- Institut für Materialphysik im Weltraum, Deutsches Zentrum für Luft- und Raumfahrt (DLR), 82234 Weßling, Germany
| | - I Laut
- Institut für Materialphysik im Weltraum, Deutsches Zentrum für Luft- und Raumfahrt (DLR), 82234 Weßling, Germany
| | - S K Zhdanov
- Institut für Materialphysik im Weltraum, Deutsches Zentrum für Luft- und Raumfahrt (DLR), 82234 Weßling, Germany
| | - V Nosenko
- Institut für Materialphysik im Weltraum, Deutsches Zentrum für Luft- und Raumfahrt (DLR), 82234 Weßling, Germany
| | - H M Thomas
- Institut für Materialphysik im Weltraum, Deutsches Zentrum für Luft- und Raumfahrt (DLR), 82234 Weßling, Germany
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17
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Sukhinin GI, Fedoseev AV, Salnikov MV, Rostom A, Vasiliev MM, Petrov OF. Plasma anisotropy around a dust particle placed in an external electric field. Phys Rev E 2017; 95:063207. [PMID: 28709289 DOI: 10.1103/physreve.95.063207] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2017] [Indexed: 11/07/2022]
Abstract
A self-consistent model of plasma polarization around an isolated micron-sized dust particle under the action of an external electric field is presented. It is shown that the quasineutral condition is fulfilled and the formed volume charge totally screens the dust particle. The ion focusing and wake formation behind the dust particle are demonstrated for different ion mean free paths and the external electric fields. It is obtained that at low values of the external electric field the trapped ions play the main role in the screening of the dust particle charge. For high external electric fields, the density of trapped ions decreases and the dust particle is screened mainly by the free ions.
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Affiliation(s)
- G I Sukhinin
- Institute of Thermophysics, 630090 Novosibirsk, Russia.,Novosibirsk State University, 630090 Novosibirsk, Russia.,Joint Institute for High Temperatures, 125412 Moscow, Russia
| | - A V Fedoseev
- Institute of Thermophysics, 630090 Novosibirsk, Russia.,Joint Institute for High Temperatures, 125412 Moscow, Russia
| | - M V Salnikov
- Institute of Thermophysics, 630090 Novosibirsk, Russia
| | - A Rostom
- Novosibirsk State University, 630090 Novosibirsk, Russia
| | - M M Vasiliev
- Joint Institute for High Temperatures, 125412 Moscow, Russia
| | - O F Petrov
- Joint Institute for High Temperatures, 125412 Moscow, Russia
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18
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Ivlev AV, Kompaneets R. Instabilities in bilayer complex plasmas: Wake-induced mode coupling. Phys Rev E 2017; 95:053202. [PMID: 28618606 DOI: 10.1103/physreve.95.053202] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2017] [Indexed: 11/07/2022]
Abstract
Stability principles for bilayer complex plasmas are studied. To mimic bilayer crystals and identify the main melting mechanism of such structures, a simple binary-chain model is employed. This approach provides adequate representation of the collective effects and accurate description of the interaction nonreciprocity, associated with the wake-mediated interparticle forces. It is shown that the wake-induced coupling of the wave modes sustained in different crystalline layers can trigger the dynamical instability. Furthermore, the mode coupling is demonstrated to be a universal instability mechanism, operating also in bilayer fluids. General stability criteria for the crystalline and fluid bilayers are derived.
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Affiliation(s)
- A V Ivlev
- Max-Planck-Institut für extraterrestrische Physik, 85748 Garching, Germany
| | - R Kompaneets
- Institut für Materialphysik im Weltraum, Deutsches Zentrum für Luft- und Raumfahrt (DLR), 82234 Weßling, Germany
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19
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Lisina II, Lisin EA, Vaulina OS, Petrov OF. Self-confined particle pairs in complex plasmas. Phys Rev E 2017; 95:013202. [PMID: 28208460 DOI: 10.1103/physreve.95.013202] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2016] [Indexed: 11/07/2022]
Abstract
The liquid-crystal type of phase transition in complex plasmas has been observed repeatedly. However, more studies need to be done on the liquid-vapor transition in complex plasmas. In this paper, the phenomenon of coupling (condensation) of particles into self-confined particle pairs in an anisotropic plasma medium with ion flow is considered analytically and numerically using the Langevin molecular dynamics method. We obtain the stability conditions of the pair (bound) state depending on the interaction parameters and particle kinetic energy. It was shown that the breakup of the particle pair is very sensitive to the ratio of particle charges; for example, it is determined by the influence of the upper particle on the ion flow around the lower one. We also show that a self-confined pair of particles exists even if their total kinetic energy is much greater than the potential well depth for the pair state. This phenomenon occurs due to velocity correlation of particles, which arises with the nonreciprocity of interparticle interaction.
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Affiliation(s)
- I I Lisina
- Joint Institute for High Temperatures, Russian Academy of Sciences, Moscow 125412, Russia
| | - E A Lisin
- Joint Institute for High Temperatures, Russian Academy of Sciences, Moscow 125412, Russia
| | - O S Vaulina
- Joint Institute for High Temperatures, Russian Academy of Sciences, Moscow 125412, Russia
| | - O F Petrov
- Joint Institute for High Temperatures, Russian Academy of Sciences, Moscow 125412, Russia
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20
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Bartnick J, Kaiser A, Löwen H, Ivlev AV. Emerging activity in bilayered dispersions with wake-mediated interactions. J Chem Phys 2016; 144:224901. [DOI: 10.1063/1.4953225] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Affiliation(s)
- Jörg Bartnick
- Institut für Theoretische Physik II: Weiche Materie, Heinrich-Heine-Universität Düsseldorf, D-40225 Düsseldorf, Germany
| | - Andreas Kaiser
- Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439, USA
| | - Hartmut Löwen
- Institut für Theoretische Physik II: Weiche Materie, Heinrich-Heine-Universität Düsseldorf, D-40225 Düsseldorf, Germany
| | - Alexei V. Ivlev
- Max-Planck-Institut für Extraterrestrische Physik, D-85741 Garching, Germany
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21
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Pfeifer JC, Bischoff T, Ehlers G, Eckhardt B. Order-disorder transitions in a sheared many-body system. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2015; 92:062208. [PMID: 26764683 DOI: 10.1103/physreve.92.062208] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/17/2015] [Indexed: 06/05/2023]
Abstract
Motivated by experiments on sheared suspensions that show a transition between ordered and disordered phases, we here study the long-time behavior of a sheared and overdamped two-dimensional system of particles interacting by repulsive forces. As a function of interaction strength and shear rate we find transitions between phases with vanishing and large single-particle diffusion. In the phases with vanishing single-particle diffusion, the system evolves towards regular lattices, usually on very slow time scales. Different lattices can be approached, depending on interaction strength and forcing amplitude. The disordered state appears in parameter regions where the regular lattices are unstable. Correlation functions between the particles reveal the formation of shear bands. In contrast to single-particle densities, the spatially resolved two-particle correlation functions vary with time and allow to determine the phase within a period. As in the case of the suspensions, motion in the state with low diffusivity is essentially reversible, whereas in the state with strong diffusion it is not.
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Affiliation(s)
- Jens C Pfeifer
- Fachbereich Physik, Philipps-Universität Marburg, 35032 Marburg, Germany
| | - Tobias Bischoff
- Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, California, 91125,USA
| | - Georg Ehlers
- Fachbereich Physik, Philipps-Universität Marburg, 35032 Marburg, Germany
| | - Bruno Eckhardt
- Fachbereich Physik, Philipps-Universität Marburg, 35032 Marburg, Germany
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22
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Melzer A. Connecting the wakefield instabilities in dusty plasmas. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2014; 90:053103. [PMID: 25493893 DOI: 10.1103/physreve.90.053103] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/10/2014] [Indexed: 06/04/2023]
Abstract
The wakefield, or ion focus, formed by ions streaming past dust particles trapped in the plasma sheath leads to two types of instabilities: the Schweigert instability in multilayer systems and the mode-coupling instability that already appears in single-layer dust systems. Here, a model is presented that treats both types of instability in a common description. The parameter space for the onset of the instabilities is determined. A new variant of the mode-coupling instability is found to arise from the interaction among the layers. For weak confinement, all instabilities continuously merge into each other. For stronger confinement of the dust mainly the Schweigert type of instability is observed.
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Affiliation(s)
- André Melzer
- Institut für Physik, Ernst-Moritz-Arndt-Universität Greifswald, 17489 Greifswald, Germany
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23
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Mukhopadhyay AK, Goree J. Experimental measurement of velocity correlations for two microparticles in a plasma with ion flow. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2014; 90:013102. [PMID: 25122396 DOI: 10.1103/physreve.90.013102] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/12/2014] [Indexed: 06/03/2023]
Abstract
Velocity correlations are measured in a dusty plasma with only two microparticles. These correlations allow a characterization of the oscillatory modes and an identification of the effects of ion wakes. Ion wake effects are isolated by comparing two experiments with the microparticles aligned parallel vs perpendicular to the ion flow. From records of microparticle velocities, the one- and two-particle distribution functions f(1) and f(2) are obtained, and the two-particle correlation function g(2) ≡ f(2)-f(1)f(1) is calculated. Comparing the two experiments, we find that motion is much more correlated when the microparticles are aligned with the ion flow and the character of the oscillatory modes depends on the ion flow direction due to the ion wake.
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Affiliation(s)
- Amit K Mukhopadhyay
- Department of Physics and Astronomy, The University of Iowa, Iowa City, Iowa 52242, USA
| | - J Goree
- Department of Physics and Astronomy, The University of Iowa, Iowa City, Iowa 52242, USA
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24
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25
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Melzer A, Schella A. Symbolic transfer entropy analysis of the dust interaction in the presence of wakefields in dusty plasmas. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2014; 89:041103. [PMID: 24827184 DOI: 10.1103/physreve.89.041103] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/11/2014] [Indexed: 05/27/2023]
Abstract
The method of symbolic transfer entropy has been applied to analyze the behavior of charged-particle systems under the influence of an ion focus (wakefield) in a dusty plasma. Using long-run experiments under various plasma and trapping conditions, it is revealed from the transfer entropy that information is transported from the upper particle in an ion flow to the lower. The information transfer increases with smaller interparticle distance and with reduced height in the sheath. This can be consistently explained by the formation of the ion focus by an ion flow in the sheath. From the analysis of two-particle and many-particle systems, the symbolic entropy transfer can be judged as a reliable measure for information asymmetry, and hence interaction asymmetry, in dusty plasma systems.
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Affiliation(s)
- André Melzer
- Institut für Physik, Ernst-Moritz-Arndt-Universität Greifswald, 17489 Greifswald, Germany
| | - André Schella
- Institut für Physik, Ernst-Moritz-Arndt-Universität Greifswald, 17489 Greifswald, Germany
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26
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Melzer A, Schella A, Mulsow M. Nonequilibrium finite dust clusters: connecting normal modes and wakefields. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2014; 89:013109. [PMID: 24580348 DOI: 10.1103/physreve.89.013109] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/14/2013] [Indexed: 06/03/2023]
Abstract
The dynamic properties of finite three-dimensional dust clusters in a dusty plasma under the influence of an ion focus are studied by normal modes. The mode analysis has been extended to account for the ion focus using the point-charge model for the horizontal interaction of the dust particles. From that, an analytical model for a few-particle system is derived accounting for three distinct dynamical regimes at different focus strengths, namely, absolutely unstable and fully stable configurations as well as an unstable oscillatory regime. The techniques of normal mode analysis (NMA) and instantaneous normal modes (INM) extended by the ion focus have been applied to dust systems in the experiment and compared to the model. From this, the ion focus strength has been derived. The specific sensitivity of NMA and INM allows one to identify equilibrium configurations in this nonequilibrium environment for these finite clusters.
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Affiliation(s)
- André Melzer
- Institut für Physik, Ernst-Moritz-Arndt-Universität Greifswald, 17489 Greifswald, Germany
| | - André Schella
- Institut für Physik, Ernst-Moritz-Arndt-Universität Greifswald, 17489 Greifswald, Germany
| | - Matthias Mulsow
- Institut für Physik, Ernst-Moritz-Arndt-Universität Greifswald, 17489 Greifswald, Germany
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27
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28
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Hutchinson IH. Intergrain forces in low-Mach-number plasma wakes. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2012; 85:066409. [PMID: 23005230 DOI: 10.1103/physreve.85.066409] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/24/2012] [Indexed: 06/01/2023]
Abstract
Large-scale particle-in-cell calculations of the plasma wake interactions of two negatively charged grains smaller than the Debye length are carried out using the coptic code over a wide range of subsonic plasma flow velocities. In plasmas with the temperature ratio T(e)/T(i)=100, it is found that a single grain's oscillatory wake disappears for flow Mach numbers M less than approximately 0.3, which is the parameter regime where Landau damping is expected to be strong. Neutral collisions suppress potential oscillations above M=0.3, but not the trailing attractive potential peak caused by ion focusing. The transverse (grain-aligning) force on a downstream particle in the wake of another is obtained rigorously from the code in three-dimensional simulations. It shows general agreement with the force that would be deduced from the single-grain wake potential gradient. Except for relatively large grains in the nonlinear collisional regime, the grain-aligning force is very small for slow flow.
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Affiliation(s)
- I H Hutchinson
- Plasma Science and Fusion Center and Department of Nuclear Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
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29
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Gu F, Wang HJ, Li JT. Density functional theory for the ground state of spherically confined dusty plasma. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2012; 85:056402. [PMID: 23004874 DOI: 10.1103/physreve.85.056402] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/27/2012] [Revised: 03/19/2012] [Indexed: 06/01/2023]
Abstract
The spatial structure of dusty plasma confined in a spherical microcavity has been investigated by use of the density functional theory for classical fluids, in which all particles undergo an isotropic harmonic potential and the interparticle interaction is described by the hard-core Yukawa potential. The fundamental measure theory of Rosenfeld and its modified versions have been used in the energy functional to incorporate hard-core interactions between particles. Based on the variational principle, the equilibrium density profile can be obtained by use of an iteration calculation with the average density of particles as an input. In terms of density profiles presented under various conditions, the roles of the trapped parameter, coupling parameter, screening parameter, and the average number density of particles are discussed, and significant influences of these factors on the structure of confined dusty plasma are found.
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Affiliation(s)
- Fang Gu
- College of Chemistry and Environment Science, Hebei University, Baoding, People's Republic of China
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30
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Schella A, Miksch T, Melzer A, Schablinski J, Block D, Piel A, Thomsen H, Ludwig P, Bonitz M. Melting scenarios for three-dimensional dusty plasma clusters. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2011; 84:056402. [PMID: 22181523 DOI: 10.1103/physreve.84.056402] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2011] [Indexed: 05/31/2023]
Abstract
The melting transition of finite three-dimensional dust clouds (Yukawa balls) from a solid-like to a liquid-like state is systematically studied with high spatial and temporal resolution of the individual grains by means of stereoscopy. Two different melting scenarios are reported: Melting is induced first by an increase of plasma power, and second by laser-induced heating. The experiments confirm that melting starts with a loss of orientational correlation, followed by a loss of the radial order upon further heating. While the plasma-power melting is driven via the ion wakefield, laser heating provides a more equilibrium scenario. The internal loss of correlations is well captured by the triple correlation function (TCF) which is insensitive to particle exchanges and the rotation of the cluster as a whole. The critical Coulomb coupling parameter for N=35 is determined as Γ(crit)≈570. The experimental findings are in good agreement with thermodynamic Monte Carlo simulations.
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Affiliation(s)
- André Schella
- Institut für Physik, Ernst-Moritz-Arndt-Universität Greifswald, Greifswald, Germany
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31
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Norman GE, Timofeev AV. Kinetic temperature of dust particle motion in gas-discharge plasma. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2011; 84:056401. [PMID: 22181522 DOI: 10.1103/physreve.84.056401] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/24/2011] [Indexed: 05/31/2023]
Abstract
A system of equations describing motion of dust particles in gas discharge plasma is formulated. This system is developed for a monolayer of dust particles with an account of dust particle charge fluctuations and features of the discharge near-electrode layer. Molecular dynamics simulation of the dust particles system is performed. A mechanism of dust particle average kinetic energy increase is suggested on the basis of theoretical analysis of the simulation results. It is shown that heating of dust particles' vertical motion is initiated by forced oscillations caused by the dust particles' charge fluctuations. The process of energy transfer from vertical to horizontal motion is based on the phenomenon of the parametric resonance. The combination of parametric and forced resonances explains the abnormally high values of the dust particles' kinetic energy. Estimates of frequency, amplitude, and kinetic energy of dust particles are close to the experimental values.
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Affiliation(s)
- G E Norman
- Joint Institute for High Temperatures of RAS, Moscow, Russia
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32
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Hutchinson IH. Forces on a small grain in the nonlinear plasma wake of another. PHYSICAL REVIEW LETTERS 2011; 107:095001. [PMID: 21929246 DOI: 10.1103/physrevlett.107.095001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/03/2011] [Indexed: 05/31/2023]
Abstract
The transverse force on a spherical charged grain lying in the plasma wake of another grain is analyzed to assess the importance of ion-drag perturbation, in addition to the wake-potential-gradient. The ion-drag perturbation is intrinsically one order smaller than the wake-potential force in the ratio of grain size (r(p)) to Debye length (λ(De)). So ion-drag perturbation is important only in nonlinear wakes. Rigorous particle-in-cell calculations of the force are performed in the nonlinear regime with two interacting grains. It is found that even for quite large grains, r(p)/λ(De)=0.1, the force is dominated by the wake-potential gradient. The wake-potential structure can then help explain the preferred alignment of floating dust grains.
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Affiliation(s)
- I H Hutchinson
- Plasma Science and Fusion Center and Department of Nuclear Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
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33
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Ivlev AV, Thoma MH, Räth C, Joyce G, Morfill GE. Complex plasmas in external fields: the role of non-hamiltonian interactions. PHYSICAL REVIEW LETTERS 2011; 106:155001. [PMID: 21568565 DOI: 10.1103/physrevlett.106.155001] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/28/2010] [Indexed: 05/30/2023]
Abstract
Dedicated experiments with strongly coupled complex plasmas in external electric fields were carried out under microgravity conditions using the PK-4 dc discharge setup. The focus was put on the comparative analysis of the formation of stringlike anisotropic structures due to reciprocal (hamiltonian) and nonreciprocal (non-hamiltonian) interactions between microparticles (induced by ac and dc fields, respectively). The experiments complemented by numerical simulations demonstrate that the responses of complex plasmas in these two regimes are drastically different. It is suggested that the observed difference is a manifestation of intrinsic thermodynamic openness of driven strongly coupled systems.
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Affiliation(s)
- A V Ivlev
- Max-Planck-Institut für extraterrestrische Physik, 85741 Garching, Germany
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34
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Liu B, Goree J, Feng Y. Mode coupling for phonons in a single-layer dusty plasma crystal. PHYSICAL REVIEW LETTERS 2010; 105:085004. [PMID: 20868106 DOI: 10.1103/physrevlett.105.085004] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/14/2010] [Indexed: 05/29/2023]
Abstract
New modes in a dusty plasma result from coupling of differently polarized phonons. A single horizontal layer of charged microparticles, confined so that vertical as well as horizontal motions are possible, usually exhibits three modes. An experiment shows that mode coupling leads to a new hybrid mode and another new mode. Coupling also leads to a recently reported hybrid mode and nondispersive mode, shown here to occur in an unmelted lattice. A linear theory based on ion wakes is able to predict some, but not all, of these modes. Other multiphase systems could exhibit similar mode coupling.
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Affiliation(s)
- Bin Liu
- Department of Physics and Astronomy, The University of Iowa, Iowa City, Iowa 52242, USA
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35
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Couëdel L, Nosenko V, Ivlev AV, Zhdanov SK, Thomas HM, Morfill GE. Direct observation of mode-coupling instability in two-dimensional plasma crystals. PHYSICAL REVIEW LETTERS 2010; 104:195001. [PMID: 20866969 DOI: 10.1103/physrevlett.104.195001] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/08/2010] [Indexed: 05/29/2023]
Abstract
Dedicated experiments on melting of two-dimensional plasma crystals were carried out. The melting was always accompanied by spontaneous growth of the particle kinetic energy, suggesting a universal plasma-driven mechanism underlying the process. By measuring three principal dust-lattice wave modes simultaneously, it is unambiguously demonstrated that the melting occurs due to the resonance coupling between two of the dust-lattice modes. The variation of the wave modes with the experimental conditions, including the emergence of the resonant (hybrid) branch, reveals exceptionally good agreement with the theory of mode-coupling instability.
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Affiliation(s)
- L Couëdel
- Max Planck Institute for Extraterrestrial Physics, 85741 Garching, Germany.
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36
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Donkó Z, Goree J, Hartmann P, Liu B. Time-correlation functions and transport coefficients of two-dimensional Yukawa liquids. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2009; 79:026401. [PMID: 19391849 DOI: 10.1103/physreve.79.026401] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/10/2007] [Revised: 10/10/2008] [Indexed: 05/27/2023]
Abstract
The existence of coefficients for diffusion, viscosity, and thermal conductivity is examined for two-dimensional (2D) liquids. Equilibrium molecular dynamics simulations are performed using a Yukawa potential and the long-time behavior of autocorrelation functions is tested. Advances reported here as compared to previous 2D Yukawa liquid simulations include an assessment of the thermal conductivity, using a larger system size to allow meaningful examination of longer times, and development of improved analysis methods. We find that the transport coefficient exists for diffusion at high temperature and viscosity at low temperature, but not in the opposite limits. The thermal conductivity coefficient does not appear to exist at high temperature. Further advances in computing power could improve these assessments by allowing even larger system sizes and longer time series.
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Affiliation(s)
- Z Donkó
- Research Institute for Solid State Physics and Optics of the Hungarian Academy of Sciences, H-1525 Budapest, P.O. Box 49, Hungary
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37
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Miloch WJ, Vladimirov SV, Pécseli HL, Trulsen J. Numerical simulations of potential distribution for elongated insulating dust being charged by drifting plasmas. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2008; 78:036411. [PMID: 18851173 DOI: 10.1103/physreve.78.036411] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/04/2008] [Indexed: 05/26/2023]
Abstract
The potential distributions surrounding elongated insulating dust grains being charged by supersonic plasma flows are studied using the particle-in-cell method. The plasma flow introduces an asymmetry in the dust charging. This leads to a complex surface charge distribution on the dust, and to ion focusing in the wake region. We demonstrate that the charge and potential distributions on the dust surface and the wake behind the dust depend on the rod length and dust inclination angle with respect to the flow. The role of the surface charge distribution in the interactions between insulating rods in a plasma is discussed. Our simulations are carried out in two spatial dimensions, treating ions and electrons as individual particles.
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Affiliation(s)
- W J Miloch
- Institute of Theoretical Astrophysics, University of Oslo, Box 1029 Blindern, N-0315 Oslo, Norway
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38
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Donkó Z, Hartmann P. Shear viscosity of strongly coupled Yukawa liquids. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2008; 78:026408. [PMID: 18850947 DOI: 10.1103/physreve.78.026408] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/10/2008] [Indexed: 05/26/2023]
Abstract
We present molecular-dynamics calculations of the shear viscosity of three-dimensional strongly coupled Yukawa liquids which are frequently used as a model system of complex plasmas. The results obtained using two independent nonequilibrium simulation methods are critically compared with each other and with earlier published data for a wide range of plasma coupling (Gamma) and screening (kappa) parameters. The non-Newtonian behavior of the liquid, manifested as a decrease of the shear viscosity with increasing shear rate (shear thinning), and the validity of the Stokes-Einstein relation at high coupling strength are also demonstrated.
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Affiliation(s)
- Z Donkó
- Research Institute for Solid State Physics and Optics of the Hungarian Academy of Sciences, H-1525 Budapest, P.O. Box 49, Hungary
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39
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Miloch WJ, Vladimirov SV, Pécseli HL, Trulsen J. Wake behind dust grains in flowing plasmas with a directed photon flux. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2008; 77:065401. [PMID: 18643327 DOI: 10.1103/physreve.77.065401] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/15/2008] [Indexed: 05/26/2023]
Abstract
The wake behind conducting dust grains in a supersonic plasma flow with a directed photon flux is studied by the particle-in-cell method. The electron emission leads to a positive charge on the dust. The resulting plasma wake differs significantly from the case without photoelectrons. This wake is studied for different photon fluxes and different angles between the incoming unidirectional photons and the plasma flow velocity. The simulations are carried out in two spatial dimensions, treating ions and electrons as individual particles.
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Affiliation(s)
- W J Miloch
- Institute of Theoretical Astrophysics, University of Oslo, Box 1029 Blindern, N-0315 Oslo, Norway
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40
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Miloch WJ, Trulsen J, Pécseli HL. Numerical studies of ion focusing behind macroscopic obstacles in a supersonic plasma flow. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2008; 77:056408. [PMID: 18643177 DOI: 10.1103/physreve.77.056408] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/11/2007] [Revised: 03/22/2008] [Indexed: 05/26/2023]
Abstract
We study the potential and plasma density variations around a solid object in a plasma flow, emphasizing supersonic flows. These objects can be dust grains, for instance. Conducting as well as insulating materials are considered. In a streaming plasma, a dust grain develops an electric dipole moment, which varies systematically with the relative plasma flow. The strength and direction of this dipole moment depends critically on the material. The net charge together with the electric dipole associated with the dust grains gives rise to electric fields, which affects the trajectories of nearby charged particles. The perturbation of ion orbits in streaming plasmas can give rise to a focusing of ions in the wake region facing away from the plasma flow. We study the parameter dependence of this ion focus. Our simulations are carried out in two spatial dimensions by a particle-in-cell code, treating ions and electrons as individual particles.
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Affiliation(s)
- W J Miloch
- University of Oslo, Institute of Theoretical Astrophysics, Box 1029 Blindern, N-0315 Oslo, Norway.
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Davoudabadi M, Mashayek F. Numerical modeling of dust particle configurations in a cylindrical radio-frequency plasma reactor. Phys Rev E 2008; 76:056405. [PMID: 18233774 DOI: 10.1103/physreve.76.056405] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2007] [Indexed: 11/07/2022]
Abstract
In the present work, first, plasma phase variables in a cylindrical radio-frequency (rf) plasma reactor are numerically solved using the local field approximation model. Then, equilibrium configurations of a few interacting (sub-)micron-sized dust particles are obtained by integrating the particles equations for their motion and charge, accounting for the various forces acting on each particle in a three-dimensional Lagrangian framework. Direct comparison of the results with experiment demonstrates excellent qualitative agreement. Based on the ion focus phenomenon, a physical model is formulated and proven successful in simulating the vertically aligned structures.
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Affiliation(s)
- M Davoudabadi
- Department of Mechanical and Industrial Engineering, University of Illinois at Chicago, 842 West Taylor Street, Chicago, Illinois 60607, USA
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Liu YH, Chen ZY, Yu MY, Bogaerts A. Multiple void formation in plasmas containing multispecies charged grains. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2006; 74:056401. [PMID: 17279995 DOI: 10.1103/physreve.74.056401] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/08/2006] [Indexed: 05/13/2023]
Abstract
Self-organized separation of charged-dust species in two-dimensional dusty plasmas is studied by means of molecular-dynamics simulation. The multispecies dust grains, interacting through a screened Coulomb potential with a long-range attractive component, are confined by an external quadratic potential and subjected to a radially outward ion drag force. It is found that, in general, the species are spatially separated by bandlike dust-free (or void) regions, and grains of the same species tend to populate a common shell. At large ion drag and/or large plasma screening, a central disklike void as well as concentric bandlike voids separating the different species appear. Because of the outward drag and the attractive component of the dust-dust interaction forces, highly asymmetrical states consisting of species-separated dust clumps can also exist despite the fact that all the forces are either radial or central.
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Affiliation(s)
- Y H Liu
- Department of Chemistry, University of Antwerp, Universiteitsplein 1, B-2610 Antwerp, Belgium
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Hartmann P, Kalman GJ, Donkó Z, Kutasi K. Equilibrium properties and phase diagram of two-dimensional Yukawa systems. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2005; 72:026409. [PMID: 16196720 DOI: 10.1103/physreve.72.026409] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/26/2005] [Indexed: 05/04/2023]
Abstract
Properties of two-dimensional strongly coupled Yukawa systems are explored through molecular dynamics simulations. An effective coupling coefficient gamma* for the liquid phase is introduced on the basis of the constancy of the first peak amplitude of the pair-correlation functions. Thermodynamic quantities are calculated from the pair-correlation function. The solid-liquid transition of the system is investigated through the analysis of the bond-angular order parameter. The static structure function satisfies consistency relation, attesting to the reliability of the computational method. The response is shown to be governed by the correlational part of the inverse compressibility. An analysis of the velocity autocorrelation demonstrates that this latter also exhibits a universal behavior.
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Affiliation(s)
- P Hartmann
- Research Institute for Solid State Physics and Optics of the Hungarian Academy of Sciences, H-1525 Budapest, P.O. Box 49, Hungary
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Arp O, Block D, Piel A, Melzer A. Dust Coulomb balls: three-dimensional plasma crystals. PHYSICAL REVIEW LETTERS 2004; 93:165004. [PMID: 15524998 DOI: 10.1103/physrevlett.93.165004] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/10/2004] [Indexed: 05/24/2023]
Abstract
First experimental investigations of spherical three-dimensional plasma crystals consisting of hundreds or thousands of micrometer-sized polymer particles suspended in a radio-frequency gas discharge are described. These "Coulomb balls" are not subject to the formation of dust-free regions (voids) and have an unusual structure of nested crystalline shells. While small systems are in a solid phase, large systems show melting effects.
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Affiliation(s)
- Oliver Arp
- IEAP, Christian-Albrechts-Universität, D-24098 Kiel, Germany.
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Donkó Z, Hartmann P, Kalman GJ. Collective modes of quasi-two-dimensional Yukawa liquids. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2004; 69:065401. [PMID: 15244656 DOI: 10.1103/physreve.69.065401] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2003] [Indexed: 05/24/2023]
Abstract
Particles in dusty plasmas are often confined to a quasi-two-dimensional arrangement. In such layers--besides the formation of compressional and (in-plane) shear waves--an additional collective excitation may also show up, as small-amplitude oscillations of the particles perpendicular to the plane are also possible. We explore through molecular dynamics simulations the properties (fluctuation spectra, dispersion relation, Einstein frequency) of this out-of-plane transverse mode in the strongly coupled liquid phase of Yukawa systems.
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Affiliation(s)
- Z Donkó
- Research Institute for Solid State Physics and Optics, Hungarian Academy of Sciences, P.O. Box 49, H-1525 Budapest, Hungary
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Hebner GA, Riley ME. Structure of the ion wakefield in dusty plasmas. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2004; 69:026405. [PMID: 14995564 DOI: 10.1103/physreve.69.026405] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/08/2003] [Indexed: 05/24/2023]
Abstract
The magnitude and structure of the ion wakefield potential below a single negatively charged dust particle levitated in the plasma sheath region were measured using a test particle. Attractive and repulsive components of the interaction force were extracted from a trajectory analysis of low-energy collisions between different mass particles in a well-defined electrostatic potential that constrained the dynamics of the collisions to one dimension. As the vertical spacing between the particles increased, the peak attractive force decreased and the width of the potential increased. For the largest vertical separations measured in this study, the lower particle does not form a vertical pair with the upper particle but rather has an equilibrium position offset from the bottom of the parabolic potential confining well.
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Affiliation(s)
- G A Hebner
- Sandia National Laboratories, Albuquerque, NM 87185-1423, USA
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Hebner GA, Riley ME. Measurement of attractive interactions produced by the ion wakefield in dusty plasmas using a constrained collision geometry. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2003; 68:046401. [PMID: 14683048 DOI: 10.1103/physreve.68.046401] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/28/2003] [Indexed: 05/24/2023]
Abstract
Plasma dust particle interactions, charges, and screening lengths are derived from measurements of time-dependent particle positions in a simplified geometry. The magnitude and structure of the ion wakefield potential below a negatively charged dust particle levitated in the plasma sheath region were measured as functions of the pressure and interparticle spacing. Attractive and repulsive components of the interaction force were extracted from a trajectory analysis of low-energy dust collisions between different mass particles in a well-defined electrostatic potential that constrained the dynamics of the collisions to be one-dimensional. Typical peak attractions varied between 60 and 230 fN while the peak particle-particle repulsion was on the order of 60 fN. Random thermal motion of the particles contributed to observable rates for transitions between different equilibrium configurations of vertically separated particles. The influence of nearest- and non-nearest-neighbor interactions on calculated particle parameters is examined using several methods.
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Affiliation(s)
- G A Hebner
- Sandia National Laboratories, Albuquerque, New Mexico 87185-1423, USA
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Hebner GA, Riley ME, Marder BM. Dynamic probe of dust wakefield interactions using constrained collisions. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2003; 68:016403. [PMID: 12935254 DOI: 10.1103/physreve.68.016403] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/23/2003] [Indexed: 05/24/2023]
Abstract
The magnitude and the structure of the ion-wakefield potential below a negatively charged dust particle levitated in the plasma-sheath region have been determined. Attractive and repulsive components of the interaction force were extracted from a trajectory analysis of low-energy dust collisions in a well-defined electrostatic potential, which constrained the dynamics of the collisions to be one dimensional. The peak attraction was on the order of 100 fN. The structure of the ion-wakefield-induced attractive potential was significantly different from a screened-Coulomb repulsive potential.
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Affiliation(s)
- G A Hebner
- Sandia National Laboratories, Albuquerque, New Mexico 87185-1423, USA
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Donkó Z, Kalman GJ, Hartmann P, Golden KI, Kutasi K. Dynamical structure functions, collective modes, and energy gap in charged-particle bilayers. PHYSICAL REVIEW LETTERS 2003; 90:226804. [PMID: 12857333 DOI: 10.1103/physrevlett.90.226804] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/12/2002] [Revised: 03/06/2003] [Indexed: 05/24/2023]
Abstract
The dynamical properties of strongly coupled charged-particle bilayers are investigated by molecular dynamics (MD) simulation and theoretical analysis. The spectra of the current correlation functions show the existence of two (in-phase and out-of-phase) longitudinal and two (in-phase and out-of-phase) transverse collective modes. The out-of-phase modes possess finite frequencies at wave numbers k-->0, confirming the existence of the predicted long-wavelength energy gap in the bilayer system. A theoretical model based on an extended Feynman ansatz for the dynamical structure functions provides predictions on the strength of the collective modes that are verified by the MD experiment.
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Affiliation(s)
- Z Donkó
- Research Institute for Solid State Physics and Optics of the Hungarian Academy of Sciences, P.O. Box 49, H-1525 Budapest, Hungary
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Melzer A. Mode spectra of thermally excited two-dimensional dust Coulomb clusters. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2003; 67:016411. [PMID: 12636615 DOI: 10.1103/physreve.67.016411] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/26/2002] [Indexed: 05/24/2023]
Abstract
The mode spectra of finite Coulomb clusters, confined systems of charged microspheres in a complex plasma, have been determined experimentally. The spectral power density of all possible modes has been measured for particle numbers between N=3 and N=145 under different plasma conditions. The agreement between measured and calculated mode frequencies is found to be very good. From this, the parameters of the particle interaction, like particle charge and screening strength, have been extracted quantitatively. In addition, the particle and mode temperatures have been obtained. The modes and the particles show the same temperature and the principle of equipartitition holds for these systems. Moreover, certain modes of interest have been compared among the different clusters, as there are the breathing mode and intershell rotation as well as the lowest- and highest-frequency modes. Moreover, the mode-integrated spectrum shows two broad maxima which are explained from "shearlike" or "compressionlike" modes. From this analysis, the transition from finite number to crystal-like properties is observed to occur around N=12 particles. Finally, a model to visualize the transition from normal mode oscillations to wave dispersions in a 2D lattice has been proposed.
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Affiliation(s)
- A Melzer
- Institut für Experimentelle und Angewandte Physik, Christian-Albrechts-Universität Kiel, 24098 Kiel, Germany.
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