Dynamics of isotropic and drifting plasmas in the vicinity and within two-dimensional finite dust clusters

Abstract

2D finite dust clusters are systems of small number of charged grains immersed in the plasma. The particle-in-cell (PIC) simulations are used to study the plasma structure, potential field and distributions of ion, electron and charge density within a dust cluster consisting of 19 grains in the absence and presence of a directed ion flow. In the isotropic plasma, an energetically stable configuration of this 2D finite dust cluster is found with overlapping ion clouds within the cluster's area. The supersonic ion flow transforms the common potential well to a shallow oval basin with the formation of an elongated potential hill behind the dust cluster. The common wake region with strong ion focusing is developed with the number density of ions significantly exceeding that in bulk plasma and within a cluster. The region within a dust cluster remains highly depleted of electrons even at supersonic ion flows. The charge on one of grains switches to a positive value. The kinetic-level PIC results provide insights into development of instabilities that can initiate the cluster reorganization, disordering and melting.

Plasma flow around and charge distribution of a dust cluster in a rf discharge

“…In twoparticle chains it has been found numerically that the negative charge of the downstream grain is reduced because the ion focus of the upstream grain increases the ion current onto the grain 19,20 . Miloshevsky et al 21,22 investigated the charging of a rigid two-dimensional hexagonal dust cluster consisting of 19 dust grains and its impact on the plasma environment with a 2d PIC/MD simulation. In absence of a streaming plasma (isotropic case) an energetically favorable configuration of the dust cluster was found for an inter-particle distance between dust grains of ∼ 0.6λ De due to the creation of a potential well by overlapping ion clouds around each dust grain.…”

“…However, most studies assume that dust particles are placed into a homogeneous background plasma with constant ion flow, while also neglecting ion-neutral collisional effects 10,24 . The number of dust particles under investigation were mostly a few and their arrangements often in artificial simple geometry like chains 11,19,25 or regular lattices 19,22,23,26 . The plasma sheath region where the dust grains are located has highly inhomogeneous ion and electron densities, a non-zero electric field, non-Maxwellian electron distribution 27,28 , as well as a complex ion velocity distribution 29 due to their acceleration in the sheath.…”

A treecode to simulate dust–plasma interactions

“…Similar complexity is faced in all other aspects of dust-plasma interactions; for example in calculating the drag force of the plasma on the dust, the plasma response to the dust, and wave propagation in dusty plasmas. Only computer simulations can provide complete models of the dust-plasma interactions, and to this end several particle-in cell (PIC) codes have been developed [13][14][15][16][17][18][19]. The most widely used of these, SCEPTIC, shows excellent agreement with the OML and SOML models in the appropriate limits [20].…”

Dynamical heterogeneities of cold 2D Yukawa liquids

“…Besides the Yukawa repulsion, much more complicated interactions between dust grains have been exper imentally studied recently, as in [22]. Various simulations have been performed to study processes in dusty plasmas [23][24][25][26][27][28][29][30][31], such as transport properties [32][33][34][35][36][37][38][39]. Due to the extremely low charge-to-mass ratio, dust grains are the strongly coupled, so that they would exhibit properties of liquids [40][41][42][43][44][45][46][47] and solids [16,[48][49][50][51][52][53][54].…”