Dynamical processes in complex plasmas

Abstract

In this review, a systematic overview of dynamical processes in complex (dusty) plasmas is given. Complex plasmas consist of electrons, ions, neutrals, and microparticles of nanometre to micrometre size, which are responsible for the unusual properties of this kind of plasmas, such as the formation of liquid or solid phases at strong electrostatic coupling. The examples represent the progress in this field within the last five years and mostly such cases were chosen, in which experimental results could be compared with theory or where the phenomenon has a diagnostic application. The presentation begins with single particle effects, where levitation, confinement in plasma traps, charging, and oscillations are involved. It is shown that vertical oscillations can be used for particle charge measurements. Nonlinear and parametric effects as well as self-excited oscillations are discussed. Then the interaction force between the particulates is explored in few-particle systems. Scattering experiments show that the interaction in the levitation plane can be described by shielded Yukawatype potentials, while the vertical interaction is governed by additional attractive wake fields. The latter are shown to be asymmetric and lead to the formation of vertical strings. The normal modes of one-dimensional or two-dimensional particle arrangements are useful tools for diagnostics. Many-particle effects are discussed in terms of low-frequency electrostatic waves. The dust-acoustic wave, the dust ion-acoustic wave, and two types of dust lattice waves (shear and compressional) are discussed with respect to diagnostic applications, among them Mach cones in plasma crystals. Laser methods are now established for the excitation of such modes. Two novel types of instabilities, the wakefield instability and the void-forming instability, as well as first results on dust ion-acoustic shocks are presented.

Numerical simulations of the charging of dust particles by contact with hot plasmas

“…The interactions between dust particles and warm plasmas represent a variety of often very complicated problems, where not all questions are amenable for theoretical or analytical studies, not even when individual dust particles are considered (Piel and Melzer, 2002;Fortov et al, 2005). In the present work we analyze the charging of a single dust particle by numerical methods.…”

Structure and Phase Transitions of Yukawa Balls

“…7. The potential barrier for moving a particle inwards from (27,4) to (26,5) [lowest curve] shows where the particle returns; interestingly the sharp increase at r 0 ≈ 0.85 is matching the return point of r = 0.39mm in the experiment, cf. Fig.…”

“…∆ E/N config. 3.030266 (27, 4) 0.000479 (26,5) 0.000006 (27,4) Table 1 Energy difference between metastable states and the ground state (the ground state and its energy is given by bold numbers) as seen in Fig. 3.…”

Molecular dynamics of Yukawa liquids in gravitation: Equilibrium, Instability and Transport

“…We also neglect wake field induced attraction (Melzer et al 2000b;Hebner et al 2003;Hebner and Riley 2004) found in the sheath region and the effect of non-uniform sheath electric field on the dust grains (Melzer et al 1994;Piel and Melzer 2002). We use single mass and single size grains under uniform gravity condition.…”