Screening of dust grains in a weakly ionized gas: Effects of charging by plasma currents

Abstract

Screening and charging of a grain in a weakly ionized plasma background are studied within the drift-diffusion approximation. The computations evidence that the account of grain charging results in a distinct qualitative change in the screened field as compared to the thermodynamically equilibrium case of a grain with a constant charge. The stationary grain charge as well as the field within the sheath around the grain are shown to be almost independent of the type of boundary conditions (for relatively low ionization rates and small grain sizes), whereas the asymptotical behavior of the effective field is rather sensitive to them.

Basic Processes in Complex (Dusty) Plasmas: Charging, Interactions, and Ion Drag Force

“…For example, it is well known, that in strongly collisional plasmas the far asymptote of the potential exhibits a Coulomb-like decay [71,[89][90][91], instead of the ∝ r −2 decay in the collisionless limit. Moreover, the long-range asymptote of the electric potential is approximately proportional to the collected ion flux (in the absence of plasma production and loss in the vicinity of the particle).…”

Ion drag force on a small grain in highly collisional weakly anisotropic plasma: Effect of plasma production and loss mechanisms

“…57 indicate that these effects do not contribute substantially to the collected ion flux, provided the ionization rate is not too high and the grain size is not too large ͑a Շ D ͒. 57 indicate that these effects do not contribute substantially to the collected ion flux, provided the ionization rate is not too high and the grain size is not too large ͑a Շ D ͒.…”

Electrostatic potential behind a macroparticle in a drifting collisional plasma: Effect of plasma absorption

“…In isotropic collisional plasmas, the elctrostatic potential around an absorbing body in the absence of ionization/recombination processes in its vicinity has an even more slowly decaying ϰr −1 long-range asymptote. [17][18][19][20][21] However, complex plasmas are very often subject to self-consistent large-scale electric fields that induce plasma fluxes relative to the ͑often stationary͒ grain component. These flows, in addition to a direct dragging influence, are also responsible for the generation of collective plasma processes such as wake formation downstream from the grains, which strongly modify the electrostatic interaction compared to the isotropic case.…”