Potential of a moving test charge in a dusty plasma in the presence of grain size distribution and grain charging dynamics

摘要

It is well known that the form of grain size distribution strongly influencesthe linear dielectric response of a dusty plasma. In previous results [IEEETrans. Plasma Sci. 29, 182 (2001)], it was shown that for a class of sizedistributions, there is an equivalence to a Lorentzian distribution ofmono-sized particles. The electrostatic response to a slowly moving testcharge, using a second order approximation can then be found [Phys. Lett. A305, 79 (2002)]. It is also well known [Phys. Plasmas 10, 3484 (2003)] that thedynamical charging of grains in a dusty plasma enhances the shielding of a testcharge. It seems natural at this stage to seek the combined effects of grainsize distribution and grain charging dynamics to a test charge moving throughthe dusty plasma. Here we consider the effects of both grain size distributionand dynamical grain charging to a test charge moving slowly in a dusty plasmaby expressing the plasma dielectric response as a function of both grain sizedistribution and grain charging dynamics. Both analytical as well as thenumerical results are presented. It is interesting to note that the previousresults can be retrieved by choosing appropriate values for differentparameters. This kind of study is relevant for both laboratory and spaceplasmas.