Melting of dusty plasma crystals in oscillating external fields

Hoffmann, G. P.; Löwen, Hartmut

doi:10.1088/0953-8984/12/33/304

Cited by 12 publications

(12 citation statements)

References 33 publications

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“…Another option for future study is to superimpose more external fields (e.g. an external electric field) to the gravitational field in order to controll the response of the system even more 77 . The latter set-up is relevant for electronic ink 78,79 .…”

Section: Discussionmentioning

confidence: 99%

Soft repulsive mixtures under gravity: Brazil-nut effect, depletion bubbles, boundary layering, nonequilibrium shaking

Kruppa

Neuhaus

Messina

et al. 2012

The Journal of Chemical Physics

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A binary mixture of particles interacting via long-ranged repulsive forces is studied in gravity by computer simulation and theory. The more repulsive A-particles create a depletion zone of less repulsive B-particles around them reminiscent to a bubble. Applying Archimedes' principle effectively to this bubble, an A-particle can be lifted in a fluid background of Bparticles. This "depletion bubble" mechanism explains and predicts a brazil nut effect where the heavier A-particles float on top of the lighter B-particles. It also implies an effective attraction of an A-particle towards a hard container bottom wall which leads to boundary layering of A-particles. Additionally, we have studied a periodic inversion of gravity causing perpetuous mutual penetration of the mixture in a slit geometry. In this nonequilibrium case of time-dependent gravity, the boundary layering persists. Our results are based on computer simulations and density functional theory of a two-dimensional binary mixture of colloidal repulsive dipoles. The predicted effects also occur for other long-ranged repulsive interactions and in three spatial dimensions. They are therefore verifiable in settling experiments on dipolar or charged colloidal mixtures as well as in charged granulates and dusty plasmas.

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Section: Discussionmentioning

confidence: 99%

Soft repulsive mixtures under gravity: Brazil-nut effect, depletion bubbles, boundary layering, nonequilibrium shaking

Kruppa

Neuhaus

Messina

et al. 2012

The Journal of Chemical Physics

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“…It is possible only to make some estimates since the real value of the ion drift velocity is unknown at least for the experiments performed so far. We get for the collective Γ d,cr for experiments on plasma crystals in radio frequency (RF) discharges and glow discharges [1][2][3][4][5][6][7][8][9][10][11][12] Γ d,cr ≈ 10 4 − 10 3 and in dense plasmas such as combustion plasma [3] we get Γ d,cr ≈ 1. This value of the critical value of the coupling constant and the tendency of a decrease of the critical value of the coupling constant with an increase of pressure is in qualitative agreement with observations (see detail description of experiments in [1][2][3][4][5][6][7][8][9][10][11][12]).…”

Section: Discussionmentioning

confidence: 99%

“…At present the phase transitions in complex plasmas (consisting from the dust particles, electron, ions and neutral atoms) are discovered experimentally [1][2][3][4][5][6][7][8][9][10][11][12] with a formation of plasma crystal and plasma liquid states. The complexity of the system does not allow to rely on the existing numerical MD simulations [13][14][15] or on the so-called One Component Plasma (OCP) approach [16] or on other numerical codes to compare the experimental results with computations.…”

Section: Introduction Statement Of the Problemmentioning

confidence: 99%

Van der Waal's approach in the theory of phase transitions in complex plasmas

Цытович¹,

Morfill

Ivlev

2003

Contrib. Plasma Phys.

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Van der Waal's approach is used to describe the equation of state of complex plasmas with dust-dust interactions including: the screened Coulomb interaction, long range non-collective repulsion, shadow non-collective attraction and collective interactions. For both cases, where either the collective or non-collective dust-dust attraction is present, the critical values of the coupling parameteris the dust charge, n d is the dust density and T d is the dust temperature). The critical values of Γ depend on effectiveness of the attraction and for non-collective attraction depend also on the size of the system. In substantially large complex plasma systems where the transitions to the crystal and liquid states were observed the collective attraction is operating and for small sizes systems corresponding to the complex plasma clusters the non-collective attraction is operating. The theoretical results obtained from Van der Waal's approach are compared with observations. It is shown that the phase transitions are not possible for a pure screened Coulomb (Yukawa) interactions.

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“…Note that within this simple Langevin picture, hydrodynamic interactions are ignored. We solve the Langevin equations of motion by Brownian dynamics simulations [44,45,46] using a finite time-step and the technique of Ermak [47,48]. We use a square cell of length with periodic boundary conditions.…”

Section: Interface Instability In Oppositely Driven Colloidal Mixturesmentioning

confidence: 99%

Charged colloids and polyelectrolytes: from statics to electrokinetics

Löwen

Esztermann

Wysocki

et al. 2005

J. Phys.: Conf. Ser.

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Experimental study of granular convection in (real) two-dimension Brazil-nut effect H A C Wibowo, T N Ain, Y P Nugraha et al. Abstract.A review is given on recent studies of charged colloidal suspensions and polyelectrolytes both in static and non-equilibrium situations. As far as static equilibrium situations are concerned, we discuss three different problems: 1) Sedimentation density profiles in charged suspensions are shown to exhibit a stretched non-bariometric wing at large heights and binary suspensions under gravity can exhibit an analog of the brazil-nut effect known from granular matter, i.e. the heavier particles settle on top of the lighter ones. 2) Soft polyelectrolyte systems like polyelectrolyte stars and microgels show an ultra-soft effective interaction and this results into an unusual equilibrium phase diagram including reentrant melting transitions and stable open crystalline lattices.3) The freezing transition in bilayers of confined charged suspensions is discussed and a reentrant behaviour is obtained. As far as nonequilibrium problems are concerned, we discuss an interface instability in oppositely driven colloidal mixtures and discuss possible approaches to simulate electrokinetic effects in charged suspensions.

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Melting of dusty plasma crystals in oscillating external fields

Cited by 12 publications

References 33 publications

Soft repulsive mixtures under gravity: Brazil-nut effect, depletion bubbles, boundary layering, nonequilibrium shaking

Soft repulsive mixtures under gravity: Brazil-nut effect, depletion bubbles, boundary layering, nonequilibrium shaking

Van der Waal's approach in the theory of phase transitions in complex plasmas

Charged colloids and polyelectrolytes: from statics to electrokinetics

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