Energy exchange in systems of particles with nonreciprocal interaction
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TICAL, NONLINEAR, AND SOFT MATTER PHYSICS
Energy Exchange in Systems of Particles with Nonreciprocal Interaction O. S. Vaulinaa,b, I. I. Lisinaa,b*, and E. A. Lisina a b Moscow
Joint Institute for High Temperatures, Russian Academy of Sciences, Moscow, 125412 Russia Institute of Physics and Technology, Institutskii per. 9, Dolgoprudnyi, Moscow oblast, 141700 Russia *e-mail: [email protected] Received April 30, 2015
Abstract—A model is proposed to describe the sources of additional kinetic energy and its redistribution in systems of particles with a nonreciprocal interaction. The proposed model is shown to explain the qualitative specific features of the dust particle dynamics in the sheath region of an RF discharge. Prominence is given to the systems of particles with a quasi-dipole–dipole interaction, which is similar to the interaction induced by the ion focusing effects that occur in experiments on a laboratory dusty plasma, and with the shadow interaction caused by thermophoretic forces and Le Sage’s forces. DOI: 10.1134/S1063776115100210
1. INTRODUCTION The study of the conditions of formation of anisotropic structures (such as one-dimensional chain structures and quasi-two-dimensional layered structures) has received much attention in various fields of science and engineering [1–4]. Apart from fundamental aspects, the investigation of such systems is of particular applied interest in the field of nano- and microtechnologies [3–5]. The dusty plasma of gas discharges is a good experimental model for studying anisotropic structures [3, 4]. Individual chains consisting of several tens of dust particles are often observed in experiments with the induction RF discharge plasma and the dc glow discharge plasma [6, 7]. Extended monolayer and multilayer dust structures usually form in the capacitive RF discharge plasma: both chain ordering of dust particles and their hexagonal close packing can exist in the vertical section of a multilayer structure [3, 4, 8–10]. Dust particles in a laboratory plasma can acquire a stochastic kinetic energy of 1–5 eV, which is much higher than the ambient gas temperature. The main mechanisms of “anomalous heating” of dust particles are usually related to various time and spatial changes in their charges [11–16]. In most works dealing with an analysis of the conditions of formation of plasma–dust systems, researchers studied particles with an isotropic reciprocal interaction. For example, the approximation that is now most widely used to describe the interaction of dust particles in a plasma is the model of a screened Coulomb potential,
where l is the interparticle distance, eZp is the particle charge, and λD is the Debye screening length. However, this model agrees with experimental and numerical results only if the distance between two single dust particles in a plasma is small, l < 4λD [3, 4]. As distance l increases, the screening effect weakens, and interaction potential U at l ≫ λD can acquire an asymptotic power character. For example, we have U ∝ l–2 in the isotropic plasma
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