A Stokes layer, which is a flow pattern that arises in a viscous fluid adjacent to an oscillatory boundary, was observed in an experiment using a two-dimensional strongly coupled dusty plasma. Liquid conditions were maintained using laser heating, while a separate laser manipulation applied an oscillatory shear that was localized and sinusoidal. The evolution of the resulting flow was analyzed using space-time diagrams. These figures provide an intuitive visualization of a Stokes layer, including features such as the depth of penetration and wavelength. Another feature, the characteristic speed for the penetration of the oscillatory flow, also appears prominently in space-time diagrams. To model the experiment, the Maxwell-fluid model of a Stokes layer was generalized to describe a two-phase liquid. In our experiment, the phases were gas and dust, where the dust cloud was viscoelastic due to strong Coulomb coupling. The model is found to agree with the experiment, in the appearance of the space-time diagrams, and in the values of the characteristic speed, depth of penetration, and wavelength.
We report on experimental evidence of visco-elastic effects in a strongly coupled dusty plasma through investigations of the propagation characteristics of low frequency dust acoustic waves and by excitations of transverse shear waves in a DC discharge Argon plasma.
During the recent decade a steadily increasing number of papers devoted to so-called "quantum dusty plasmas" (QDP) appeared. These systems are combining the properties of dusty (i.e. micrometer to nanometer-sized particles containing) plasmas with quantum effects %(of electrons) appearing at high-density and/or low-temperature. Many exciting properties of QDP were predicted including nontrivial collective oscillations and linear and nonlinear waves. It was predicted that the results have relevance for dense astrophysical plasmas such as white dwarf stars, neutron stars, magnetars and laborator…
Dusty plasma crystals have traditionally been observed and studied in radio frequency (RF) discharge plasmas and their formation in a DC glow discharge plasma remains experimentally challenging. We report the first ever observation of a stable dusty plasma Coulomb crystal in the cathode sheath region of a DC glow discharge plasma. The observations are made in the DPEx device where crystals of mono-disperse Melamine Formaldehyde grains are produced in the background of an Argon plasma. The crystalline nature of the structure is confirmed through a host of measurements that includes the radial p…
An experimental investigation of the propagation characteristics of shock waves in an inhomogeneous dusty plasma is carried out in the Dusty Plasma Experimental (DPEx) device. A homogeneous dusty plasma, made up of poly-dispersive kaolin particles, is initially formed in a DC glow discharge Argon plasma by maintaining a dynamic equilibrium of the pumping speed and the gas feeding rate. Later, an equilibrium density inhomogeneity in the dust fluid is created by introducing an imbalance in the original dynamic equilibrium. Non-linear wave structures are then excited in this inhomogeneous dusty p…
We consider a hydrodynamic model of a quantum dusty plasma. We prove mathematically that the resulting dust ion acoustic plasma waves present the property of being conservative on average. Furthermore, we test this property numerically, confirming its validity. Using standard techniques from the study of dynamical systems, as for example the Lyapunov characteristic exponents, we investigate the chaotic dynamics of the plasma and show numerically its existence for a wide range of parameter values. Finally, we illustrate how chaotic dynamics organizes in the parameter space for fixed values of t…
The formation of the gigantic dust-acoustic rouge waves (DARWs) in an electron depleted unmagnetized opposite polarity dusty plasma system is theoretically observed for the first time. The nonlinear Schrödinger equation (derived by utilizing the reductive perturbation method) has been analytically as well as numerically analyzed to identify the basic features (viz., height, thickness, and modulational instability, etc.) of DARWs. The results obtained form this investigation should be useful in understanding the basic properties of these rouge waves which can predict to be formed in electron de…
Potential of a moving test charge in a dusty plasma in the presence of grain size distribution and grain charging dynamics
尘埃等离子体的线性介电响应受粒子尺寸分布的影响。在以前的结果[IEEE trans.Plasma Sci. 29，182（2001）]，表明对于一类尺寸分布，存在与单尺寸颗粒的洛伦兹分布的等价性。然后可以使用二阶近似法找到对缓慢移动的试探电荷的静电响应[Phys. Lett. A 305，79（2002）]。众所周知[Phys. Plasmas 10，3484（2003）]，尘埃等离子体中颗粒的动态充电增强了对试探电荷的屏蔽。在这一阶段，寻求颗粒尺寸分布和颗粒充电动力学对移动通过尘埃等离子体的试探电荷的组合效应似乎是自然的。在这里，我们考虑的晶粒尺寸分布和动态的晶粒充电的试探电荷在尘埃等离子体中缓慢移动的等离子体介电响应作为晶粒尺寸分布和晶粒充电动态的函数表示的影响。分析以及数值结果。值得注意的是，可以通过为不同的参数选择适当的值来检索以前的结果。这种研究对实验室和空间等离子体都有意义。
The ionization equation of state (IEOS) for a cloud of the dust particles in the low-pressure gas discharge under microgravity conditions is proposed. IEOS relates pairs of the parameters specific for the charged components of dusty plasma. It is based on the modified collision enhance collection model adapted for the Wigner--Seitz cell model of the dust cloud. This model takes into account the effect of ion--atom collisions on the ion current to the dust particles and assumes that the screening length for the ion--particle interaction is of the same order of magnitude as the radius of the Wig…
The basic features of dust-acoustic (DA) waves (DAWs) in four component dusty plasma system (containing inertial cold and hot dust grains, inertialess non-extensive ions and electrons) have been theoretically investigated by deriving the nonlinear Schrödinger equation. The analytic analysis under consideration demonstrates two types of modes, namely, fast and slow DA modes. The unstable domain for the fast DA mode, which can be recognized by the critical wave number ($k_c$), gives rise to the DA rogue waves (DARWs). It is observed that the amplitude and width of the DARWs are significantly mod…
The temperature of a dust ensemble in a dusty plasma is one of its most fundamental properties. Here, we present experiments using the configurational temperature as a for the temperature analysis in dusty plasmas. Using a model of the particle interactions, the configurational temperature allows us to determine the temperature of the dust ensemble from measurements of the particle positions, rather than particle velocities. The basic concept will be presented and the technique is applied to two-dimensional finite clusters as well as three-dimensional data from an extended dust cloud. Addition…
The impacts of dust density inhomogeneity and dust size distribution (DSD) on linear dust acoustic (DA) wave propagation have been investigated theoretically in an inhomogeneous unmagnetized dusty plasma having powerlaw DSD. Two different types of wave modes, viz. slow and fast mode, are found to propagate in this inhomogeneous medium. It is shown that the linear dispersion characteristics of the DA waves are substantially affected by the DSD and density inhomogeneity. Also, it is found that the phase velocity increases with increasing dust density.
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 nonlinear response analysis, while grain-grain nonlinear interactions can be determined by a multi-particle nonlinear response analysis. Here, a machine learning-based method to determine the equation of motion in the nonlinear response analysis for dust particles in plasmas is presented. Searching the parameter space in a Bayesian manner allow…
Collective excitations of rotating dusty plasma are analyzed under the quasi localized charge approximation (QLCA) framework for strongly coupled systems by explicitly accounting for the dust rotation in the analysis. Considering the firm analogy of magnetoplasmons with "rotoplasmons" established by the recent rotating dusty plasma experiments, the relaxation introduced by the rotation in their strong coupling and 2-dimensional (often introduced by gravitational sedimentation) characteristics is emphasized in their dispersion. Finite rotation version of both strong and weak coupling dispersion…
In this paper, we studied the structure and dynamics for a trilayer Yukawa crystal. We firstly studied the optimal lattice structure by comparing lattice interaction energy from different lattice distribution, after that, we did the collective mode calculation and analyzed its eigenvectors, if the lattice structure is stable, all the eigenvalues of the dynamical matrix should be positive.
The nonlinear propagation of the dust-acoustic bright and dark envelope solitons in an opposite polarity dusty plasma system (composed of non-extensive $q$-distributed electrons, isothermal ions, and positively as well as negatively charged warm dust) have been theoretically investigated. The reductive perturbation method (which is valid for a small, but finite amplitude limit) is employed to derive the nonlinear Schrödinger equation. Two types of modes (namely, fast and slow dust-acoustic (DA) modes) have been observed. The conditions for the modulational instability (MI) and its growth rate …
The modulational instability of dust-acoustic (DA) waves (DAWs), and corresponding DA rogue waves (DARWs) in a realistic space dusty plasma system (containing inertial warm positively and negatively charged dust, isothermal ions, and nonthermal kappa distributed electrons) has been theoretically investigated. The nonlinear Schrödinger (NLS) equation is derived by using reductive perturbation method for this investigation. It is observed that the dusty plasma system under consideration supports two modes, namely fast and slow modes, and that both of these two modes can be stable or unstable dep…
The standard nonlinear Schrödinger equation (NLSE) is one of the elegant equations to find the information about the modulational instability criteria of dust-ion-acoustic (DIA) waves (DIAWs) and associated DIA rogue waves (DIARWs) in a three-component dusty plasma medium having inertialess super-thermal kappa distributed electrons, and inertial warm positive ions and negative dust grains. It can be seen that under the consideration of inertial warm ions along with inertial negatively charged dust grains, the plasma system supports both fast and slow DIA modes. The charge state and number dens…
The propagation of ionic perturbations in a dusty plasma is considered through a three-species kinetic simulation approach, in which the temporal evolution of all three elements i.e. electrons, ions and dust particles are followed based on the Vlasov equation coupled with the Poisson equation. Two cases are focused upon: firstly a fully electron depleted dusty plasma, i.e., a plasma consisting of ions and dust-particles. The second case includes dusty plasmas with large electron-to-ion temperature ratios. The main features of the ionic waves in these two settings including the dispersion relat…
An interaction of upstream extra particles with a monolayer highly-ordered complex plasma is studied. A principally new abnormal turbulent wake formed behind the supersonic upstream particle is discovered. An anomalous type of the turbulence wake clearly manifests in anomalously low thermal diffusivity and two orders of magnitude larger particle kinetic temperature compared to that of the 'normal' wake (Mach cone) observed by Du et al [Europhys. Lett. 99, 55001 (2012)].
The creation of a spatially extended stable DC complex plasma crystal is a big experimental challenge and a topical area of research in the field of dusty plasmas. In this paper we describe a newly built and commissioned dusty plasma experimental device, DPEx-II, at the Institute for Plasma Research. The device can support the formation of large sized Coulomb crystals in a DC glow discharge plasma. The plasma in this L-shaped table-top glass chamber is produced between a circular anode and a long tray shaped cathode. It is characterized with the help of various electrostatic probes over a rang…
A phenomenological model using fluid theory is developed to show that the decay of two seemingly independent nonlinear structures namely the dust void and dust soliton strongly depends on the plasma ionization parameter in an unmagnetized complex plasma system. Numerical solution of model equations has shown that the evolution of dust voids and their subsequent decay in a time frame is intimately related with the ionization parameter. A similar result also holds good in case of dust solitons where stability of soliton is found to depend critically upon ionization parameter. Most importantly, i…
A theoretical model is presented to study characteristics of dust acoustic shock in a viscous, magnetized and rotating dusty plasma at both fast and slow time scales. By employing reductive perturbation technique the nonlinear Zakharov--Kuznetsov (ZK) equation has been derived for both cases when dust is inactive and dynamic (fast and slow time scales). Both electrons and ions are considered to follow kappa/Cairns distribution. It is observed that the viscosity in both cases when dust is in background and active plays as a key role in dissipation for the propagation of acoustic shock. Magnetic…
