Steady-shear-enhanced microdiffusion with multiple time scales of confined, mesoscopic, two-dimensional dusty-plasma liquids

Io, Chong-Wai; Lin, I‐Nan

doi:10.1103/physreve.80.036401

Cited by 23 publications

(11 citation statements)

References 33 publications

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“…The effect of shearing forces and liquid state viscosity were investigated in early years of dusty plasma research [8][9][10][11]. More recently, effects of shearing forces on the microstructure were experimentally investigated in greater detail including liquid flows and plastic deformations of a crystalline solid [12][13][14][15][16][17]. Here we present dusty plasma experiments providing the link between the standard, macroscopic measures used in material sciences and metallurgy to describe plastic deformations, and the detailed microscopic information provided by dusty plasma experiments.…”

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confidence: 99%

Slow Plastic Creep of 2D Dusty Plasma Solids

et al. 2014

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We report complex plasma experiments, assisted by numerical simulations, providing an alternative qualitative link between the macroscopic response of polycrystalline solid matter to small shearing forces and the possible underlying microscopic processes. In the stationary creep regime we have determined the exponents of the shear rate dependence of the shear stress and defect density, being α = 1.15 ± 0.1 and β = 2.4 ± 0.4, respectively. We show that the formation and rapid glide motion of dislocation pairs in the lattice are dominant processes.The direct in situ observation of dynamical processes in bulk condensed matter is not yet available with atomic resolution in both space and time. Femtosecond pumpprobe techniques can resolve atomic motion, atomic force microscopy can detect atoms on surfaces, diffraction methods provide information about the bulk structure, but as long no method can combine all the benefits of these techniques, we are limited to rely of phenomenological models and numerical simulations. Alternative experimental methods have already proven to be helpful for the qualitative understanding of classical collective phenomena. Charged colloids suspended in a liquid environment, and dusty plasmas (solid micron sized particles charged and levitated in gas discharge plasmas) are both interacting many-particle systems that show very similar properties to conventional atomic matter, but at time and distance scales easily and directly accessible with simple video microscopy techniques. Both methods provide insight into the microscopic (particle level) details of different phenomena. Colloid systems are characterized by over-damped dynamics, due to the liquid environment, which makes them well suited for structural and phase transition studies [1], while the weak damping in low pressure gas discharges makes dusty plasmas perfect for studies of wave-dynamics, instabilities, and other collective excitations [2].In material science and metallurgy, creep is the time dependent plastic strain at constant stress and temperature; therefore, it is a special type of plastic deformation of solid matter. In general it is a slow process driven by the thermally activated movement of dislocations (dislocation creep), vacancies (vacancy creep) or diffusion (Nabarro-Herring and Coble creep). The applied stresses are below the rapid yield stress resulting in atomic movements that are crystallographically organized. The applied temperatures are usually above 1 2 T m , where T m is the melting temperature. The time (t) evolution of the deformation (strain ε) at constant stress is often described by one of the empirical formulae(1)where ε 0 is the immediate strain and δ, ϑ and φ are creep coefficients [3]. After a short transient phase ("primary creep"), approximated as logarithmic (∼ δ ln t) or using Andrade's law (∼ ϑt 1/3 ), this describes a steady-state "secondary" creep, dominated by the last term, where the rate φ is determined by the balance of work hardening and thermal softening. Under such circumstances the ste...

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Slow Plastic Creep of 2D Dusty Plasma Solids

et al. 2014

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“…The lighter charged components of the dusty plasma (electrons and positive ions) are weakly coupled. Dusty plasmas have much in common with other strongly coupled plasmas, such as ultracold neutral plasmas 21 , and warm dense matter 22 as well.The collection of microspheres can undergo a liquid-like flow when external forces are applied by laser beams [23][24][25][26][27] . In this way, the microspheres can be driven into a shear flow-that is, a flow with a transverse gradient in the flow velocity.…”

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Strongly coupled plasmas obey the fluctuation theorem for entropy production

et al. 2017

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Fluctuation theorems 1-4 describe nonequilibrium stochastic behaviour in small systems. Whilst experiments have shown that fluctuation theorems are obeyed by single particles in liquids 5 and several other physical systems 6-10 , it has not been shown if that is the case in strongly coupled plasmas. Plasmas are said to be strongly coupled when interparticle potential energies are large compared to kinetic energies. Charged particles in such plasmas can behave collectively like liquids 11,12 , but with essential di erences, such as long-range collisions 13 . It remains unexplored whether, despite these di erences, the stochastic behaviour of strongly coupled plasmas will obey fluctuation theorems. Here we demonstrate experimentally that a strongly coupled dusty plasma obeys the fluctuation theorem of Evans, Cohen, and Morriss (ECM) 14 , which was developed for a simple liquid in a nonequilibrium steady state. This fluctuation theorem describes the entropy production arising from collisions in a steady laminar shear flow.A dusty plasma 15-17 is a four-component mixture of microspheres, electrons, positive ions, and a rarefied neutral gas, which all share a volume 18 . The microspheres, which are the heaviest of these components, develop large charges 19 so that they become strongly coupled 20 . The lighter charged components of the dusty plasma (electrons and positive ions) are weakly coupled. Dusty plasmas have much in common with other strongly coupled plasmas, such as ultracold neutral plasmas 21 , and warm dense matter 22 as well.The collection of microspheres can undergo a liquid-like flow when external forces are applied by laser beams [23][24][25][26][27] . In this way, the microspheres can be driven into a shear flow-that is, a flow with a transverse gradient in the flow velocity. In the shear flow, entropy production results from collisions between microspheres.Many fluctuation theorems centre on the rate of entropy production in nonequilibrium systems below the thermodynamic limit. Fluctuation theorems (not to be confused with the similarly named fluctuation-dissipation theorem) all spawned from the ECM fluctuation theorem; this original fluctuation theorem was developed especially for a steady-state laminar shear flow. In a shear flow, entropy production is generated by viscous heating. This viscous heating is always positive in the thermodynamic limit, but it can fluctuate briefly to negative values for a subsystem within the fluid, containing a small number of molecules. These fluctuations, with negative heating and therefore negative entropy production, have been described as violations of the second law of thermodynamics 14 .The ECM fluctuation theorem compares these negative-entropyproduction fluctuations to the more common positive fluctuations. In particular, the probabilities of these two kinds of fluctuations are predicted to have a ratio obeying 14,28 ln p(We will later summarize equation (1), which is the historically important ECM fluctuation theorem, as left-hand side equals righthand side ...

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“…9,10 Now, behaviors of 2D dusty plasmas are often studied using simulations of 2D Yukawa liquids and solids. [11][12][13][14][15][16][17][18][19] In the past two decades, the behaviors of 2D dusty plasmas have been investigated widely, from theories and simulations [11][12][13][14][15][16][17][18][19] to experiments, [20][21][22][23][24][25][26][27] as reviewed in Refs. 28-32. However, for 2D dusty plasmas, a concise analytical relationship between various physical quantities which can be easily used to derive other thermodynamical procedure is still lacking.…”

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confidence: 99%

Equations of state and diagrams of two-dimensional liquid dusty plasmas

Feng

Lin

et al. 2016

Physics of Plasmas

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Recently, the pressure of two-dimensional (2D) Yukawa liquids has been calculated from the simulations of isochores [Feng et al., J. Phys. D: Appl. Phys. 49, 235203 (2016)], which is applicable to 2D dusty plasmas. Thus, the equation of state for 2D strongly coupled liquid dusty plasmas is obtained. Isobars and isotherms of 2D liquid dusty plasmas are derived from this equation of state. For 2D liquid dusty plasmas, the surface corresponding to this equation of state has also been obtained in the 3D space of the pressure, the temperature, and the screening parameter which is related to the volume in the equilibrium state.

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Steady-shear-enhanced microdiffusion with multiple time scales of confined, mesoscopic, two-dimensional dusty-plasma liquids

Cited by 23 publications

References 33 publications

Slow Plastic Creep of 2D Dusty Plasma Solids

Slow Plastic Creep of 2D Dusty Plasma Solids

Strongly coupled plasmas obey the fluctuation theorem for entropy production

Equations of state and diagrams of two-dimensional liquid dusty plasmas

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