On the effect of ion-neutral collisions on dust grain screening in a low-pressure gas discharge plasma

Abstract

The effect of ion-neutral collisions on charging of micrometer-sized dust grains immersed in a low-pressure argon discharge plasma is studied on the basis of the Vlasov-Bhatnagar-Gross-Krook kinetic equations. The equations are solved numerically using the method described in our previous work [I. L. Semenov et al., Phys. Plasmas 18, 103707 (2011)]. A modified version of the numerical method is proposed to reduce the required computational time. Numerical calculations are carried out for typical plasma parameters used in laboratory investigations of dusty plasma. On the basis of the obtained results, the influence of collisions on the ion flux and grain charge is analyzed. A comparison of our results with those obtained using different analytical models proposed earlier is presented. In addition, applicability of simple kinetic models describing the influence of collisions on the electric potential around a dust grain [S. A. Khrapak et al., Phys. Rev. Lett. 100, 225003 (2008); A. G. Zagorodny et al. Ukr. J. Phys. 54, 1089 (2009)] is examined. The influence of ion-neutral collisions on the distribution of plasma macroparameters near the grain surface is also demonstrated.

Particle flows in a dc discharge in laboratory and microgravity conditions

“…Two important effects should be accounted for in such a model: Ion-neutral collisions and relative drift between the ions and the particle. Although, the effect of ion-neutral collisions on the particle charging has received considerable attention [31][32][33][34][35][36][37] (for a review see Ref. [10]), most of the studies have concentrated on isotropic conditions.…”

Potential around a dust grain in collisional plasma

“…There are some more papers published in the recent and earlier years which are found to deal with these kinds of issues. [12][13][14][15][16][17][18] The common approach to the study of wall plasma interaction is by solving the relevant fluid equations with proper boundary conditions. The sheath edge, separating the bulk plasma and the sheath is found to be a common boundary for starting the numerical execution.…”

Propagator integral method for plasma physics kinetic equations with practical applications

“…Even when this interaction has a small cross-section, because it is a short-range collision instead of a large-range one as the Coulombian interaction, the cumulative effect of collisions acts as a viscous media where charged particles move and exchange momentum and energy to the neutral species. This means that neutrals become important due to their high density with respect to charged species, and its evolution can be relevant to describe the plasma as a whole, specially in large time-scales, as we presented in references [24,25] and was also stated by many authors in recent years [12,95,117,128].…”

“…These descriptions are widely used in situations where collisions are not dominant or the time and length scales studied are smaller than the collisional ones, meaning that its influence is marginal. However, it is important to stress out that collisions are always present and many situations may appear where these effects cannot be neglected and may drive the dynamics of the system [19,25,94,95]. Hence, the action of the electromagnetic field, or any other force, governs the dynamics of the system.…”

“…In figure 5.1, the density for charges (ions and electrons) and neutrals respect to the total one are pictured. This large amount of neutral particles has a high influence in the plasma dynamics as it interacts with the charged species [12,25,95,117,128]. Nevertheless, due to the strong interaction between charged species, because of the large range of Coulombian interaction and the presence of the electromagnetic field a small amount of charges drastically changes the system dynamics.…”