Formation of chain structures with an anisotropic pairwise interaction between grains
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Formation of Chain Structures with an Anisotropic Pairwise Interaction between Grains I. I. Lisinaa, b and O. S. Vaulinaa, b a
Joint Institute for High Temperatures, Russian Academy of Sciences, Izhorskaya ul. 132, Moscow, 125412 Russia b Moscow Institute of Physics and Technology, Kerchenskaya ul. 1a1, Moscow, 117303 Russia email: [email protected], [email protected] Received November 15, 2013; in final form, March 15, 2014
Abstract—Results are presented from the numerical study of the processes accompanying the formation of chain structures in systems with an anisotropic pairwise interaction similar to the interaction caused by ion focusing. The simulations were performed for extended and bounded chain structures in a wide range of parameters corresponding to conditions of experiments with laboratory dusty plasma. The development of various instabilities in such systems is analyzed in detail for the first time. DOI: 10.1134/S1063780X14090050
1. INTRODUCTION Studies of conditions for the formation of highly anisotropic structures of interacting particles (such as chain or layered structures) attract considerable inter est in different fields of science and technology [1–4]. In addition to their fundamental importance, studies of such systems are of special applied interest in the field of nano and microtechnologies, as well as in designing coatings and materials with specified prop erties [3, 4]. At present, there are a lot of works devoted to the analysis of conditions for the formation of anisotropic systems (see, e.g., [5–16]). Most of them concern studies of particle systems with an isotropic pairwise interaction. Some works are devoted to the formation of chain structures having various spatial configurations [12–16]. Dusty plasma is an ionized gas containing charged micronsize grains (dust). Such plasma is widespread in nature and forms in some technological processes [3, 4]. Laboratory dusty plasma produced under con ditions of a capacitive or inductive RF discharge is a good experimental model for studying the properties of highly anisotropic structures [3, 4]. It should be noted that experiments with dusty plasma in an RF discharge demonstrate a wide variety of structural configurations of dust grains. In experi ments with plasma of a capacitive RF discharge, extended mono and multilayer dust structures usually have a pronounced hexagonal lattice in the horizontal (perpendicular to the gravity force) direction. How ever, in the vertical direction, one can observe both the chain ordering and the dense hexagonal package of dust grains in the neighboring layers [3, 4, 17, 18]. The formation of individual dust chains involving up to several tens of grains is often observed in experiments
with plasmas of an inductive RF discharge and a dc glow discharge [19, 20]. Under certain conditions (e.g., when the pressure varies or the number of grains increases), dust grains in laboratory plasma can acquire a stochastic kinetic energy of ~1–5 eV, much exceeding the temperature of the ambient
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